Gloom Stalker Ranger has the ability Umbral Sight to become invisible to creatures who rely on darkvision:

You are also adept at evading creatures that rely on darkvision. While in darkness, you are invisible to any creature that relies on darkvision to see you in that darkness.

As a reference, if I check some special monsters cards that have included in they "Senses" the words "Blindsight" (ex: Dragons), "Tremorsense" (ex: Umber Hulk) or "Truesight" (ex: Couatl), it is obviously that these monsters would be able to see the Gloom Stalker in darkness as they don't rely on darkvision to see.

In the compendium I found a skill called Devil's Sight first as a warlock invocation:

Devil’s Sight. You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet.

and then as a skill in some monster cards:

Devil’s Sight. Magical darkness doesn’t impede the devil’s darkvision.

I can understand that the warlock invocation enables him/her to see as bright as day in darkness. That means that it would see the Gloom Stalker in darkness as for the warlock that's not darkness at all.

When regarding monsters with Devil's Sight (ex: Spined Devil), besides the different description, the word "Devil's Sight" is not included in the "Senses".

My questions are:

1. Are these skills the same? Because even if the naming is the same, their description is totally different.

2. When regarding the monsters who have devil's sight is it considered a sense, meaning that it would bypass the Gloom Stalker invisibility in darkness?

My DM ruled that Devil's Sight from the Spined Devil is the same skill from warlock and a special sense and it could see me as a Gloom Stalker in darkness.

1. They are similar, but not the same.
2. It is not a sense in either case. Though for warlock, it does mean that it does not need to rely on darkvision. For devils, it just makes them able to see in magical darkness, but they still rely on darkvision.

A warlock with Devil's Sight would be able to see the gloom stalker, as they do not have Darkvision but a mechanically very similar ability.

The devil would not be able to see the gloom stalker, as their Devil's Sight modifies their Darkvision sense, which is what they would be using to see with.

Its confusing that they are named the same.

I am not sure, if the same name implies the intention to be both —Devil's Sight from warlock and devil— should be the same ability. Otherwise I know that players always set RAW above game logic, as is with Truesight and EI Witch Sight ruled similarly but different, Aarakocra Talons are "no" natural weapons etc. (It’s a bit like: God exists, because it is written in the bible! No common sense required. And if it is not in the bible, it does not exist—black swan theory.)

Does there exist something from the officials, what was intended when determining the descriptions, which could differ in text but not in the intention?

It would be logical for the game, when Devil's Sight granted to a warlock or Eldritch Adept is the same ability as that from a devil, because a fiend could grant this pact magic. It also could define Devil's Sight as a special form of Darkvision, which is able to see in non-magical as well as magical darkness, but is still a 'brighter' darkvision.

What would this come out for the gloom stalker ranger? The warlock casts darkness to set the ranger blinded and itself invisible, but when the warlock switches off the 'light' (or switches on the 'black light') the ranger is turned invisible too. There was not RAW over all, but something about a rule of cool…

P.S.: A devil, celestial, or other creature could deal with a gloom stalker by just setting something on fire, cast a fire cantrip to light the scene for a moment, or cast a light spell etc.—but let the hero shine, not the DM's slaughter feast.

A barbed devil's Devil Sight and the Warlock's Devil Sight invocation are NOT the same ability.

The barbed devil's Devil's Sight. Magical darkness doesn't impede the devil's darkvision

The warlock's Devil's Sight. You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet.

They are mechanically similar, but still different abilities.

…or just two different wordings of the same thing. Have you understood the subtext in my reply? Do you think a talon is "no" natural weapon, because the description in the PC's Aarakocra trait is missing this exact wording (compare the monster stat block’s Talon Melee Weapon Attack)? The concept behind a description is more important than the used words. There is no RAW over ROC or the words cancel any common sense in the game, if written not in an exact nerdish tone. Stop that gematria, that is not in the developers' intention!

An example from Tolkien: When he describes Earth (german Erde) as Arda, the origin of mankind from the east as his Peking man (Out of Africa came later after publishing LotR), the Alfred Wegener continental drift between the Americas and Eurasia/Africa as a greater becoming distance between Aman and Middle-Earth, placing the Sea of Helcar where later the Himalayas have raised, gives Atlantis the name Numenor, Australia the description of dark lands, using the ancient term oliphaunt for elephant, Rohirrim for polish (winged) riders [not vikings!], Anduin for Danube, white mountains for Alps, Osgiliath for Byzantium, giving Jesus the name Gandalf, Cuba the name Tol Eressea, describing the pope on the throne of Petrus steward of the true king God by the title Steward of Gondor, and the Nagasaki atomic mushroom as Barad Dur inclusive the radiation around with the eye-witness report of the red eye surrounded by smoke (watch Rhapsody in August) [okay Tolkien placed the black land into the black sea, to travel the whole silk road to Japan was a bit too far for the story line], metaphors the knowledge of this nuclear weapon as the plans of the death star in a one ring, as well as tells the immortal earlier biblical humanoid methusalems have that what later mortal humanoids have as a decent heritage in form of a darwin tubercle (woolnerian tip aka pointed ears), and you are unable to understand that a different wording is not a totally different thing, than you are not only unable to understand, why Tolkien said that he was writing about Europe, but later denied so, because the people entered the cold war instead of destroying the ring, you also would join the Gary Gygax club of misinterpreting Tolkien's enormous work of research, which is totally afar from epic fantasy like Moorcock or the Peter Jackson films. Tolkien is science, not fiction!

Nevertheless this misinterpretation created Warhammer and Dungeons & Dragons. A lot of myths are misinterpretations too, like the unicorn was once a description of a giraffe (cameleopardis) or a rhino, or that a big guy with one remaining healthy eye will not have it in the mid of his forehead (most of the cyclops had two healthy eyes). I do not complain about misinterpretations, only about people which talk about words instead of their meanings—in particular when having lost any real world connection to recognize that oliphaunt is elephant (olifant) instead of **mutant dinophant**, and that Tolkien just lined up modern science at the top of his time and mythology of this non-fictional planet beneath our feet. Watch Big Fish for ROC!

Do you know that Frankenstein's monster is Adam, gollum comes from golem (jewish for 'idiot'), Moby Dick is the thrusted messias, and the Beauty and the Beast are Eros and Psyche? Mythology has a history from the first spoken words of mankind up to modern theology and commercial products. The meaning of words is changing over time. Rutherford never found the ancient greeks' atom, dividing his atom himself in a hull and a core, but now atom has the Rutherford meaning, not its original (a-tomos = uncuttable, undividable). What now is force, once was ernergia—not to be confused with energy. The meaning of the word is more important than the specific word, if it is mentioned or not, or if the author had not considered the nitpicking of words by other people. "Blessed are those who have nothing to say and cannot be persuaded to say it" — James Russell Lowell.

Gygax and later developers were still able to understand sun blade is another description of lightsaber, tarrasque is Gojira/Godzilla (embodiment of earthquakes and a striking back nature) etc., wherever the inspiration came from, there is a real world connection, even a fictional one. They worked the process of writing rules in the in-game history, e.g. spell plague and shadowfell. Tolkien did this too, when describing his WWI experiences in the Silmarillion: barrage fire became balrog (ripping flames and smoke), tank became dragon (doors in its flanks!) etc.

How do you explain the Devil's Sight abilities of devils and warlocks, when you do not only see the words of the matrix but try to understand the concept which is described with these words?

Both have the same name. Both let you see in magical and non-magical darkness to a distance of 120 feet. The warlock's Devil's Sight doesn't deny to be a form of darkvision, nor does the devil's exclude this. Does it impede the warlock's darkvision, will the warlock be restricted to not use darkvision from drow/gnome, gloom stalker's umbral sight, goggles of night etc.? What will change, when you swap the descriptions? Both will still see in magical and non-magical darkness up to 120 feet. Will goggles of night add 60 feet to a warlock's Devil's Sight or a devil's Devil's Sight? Does the developers intended that the PotC imp can use goggles of night to see 180 feet in non-magical and magical darkness (familiars can use magic items), but its warlock master can’t use the item efficiently, because the effect will sink into the warlock’s Devil’s Sight of 120 feet? Can the devil see with its Devil's Sight only shades of gray and the warlock colors? If you rely only on words instead of their meanings, then D&D has much more traps to turn a game session into a kind of theological debate only using the bible as reference. It's a game, not the truth!

What do you think, were the thoughts and intentions of the developers, when writing these words? What was so important, to use other wordings? What game mechanics needed here to be balanced? What claim of copyright had to be avoided? Don't explain there are different words, describe what are the ideas in the heads of their authors.

Maybe the developers intended to keep the devil's stat block short and thought that the short sentence would do its job, to say the darkness spell will not help the players, but did not expect the weighing of the words they have used by their readers. Of course, in the combat and spell system you see the attempt to define the possible actions by the wording of the rules, but you do not find this exactness in racial or monster descriptions. For game balance compare the different charge handlings of a player's centaur (size medium ponytaur?) 1d4 hooves and a monstrosity centaur (size large as a horse) 3d6 pike, with 2d6 hooves are a separate attack, and can be ridden. But they try to give a centaur player the feeling to play a centaur, and also try to let you feel you are fighting a centaur monster. The Aarakocra has talons as melee weapons as a monster, but these words are missing in its racial traits, as well as its dive attack. A tiny carpet of flying can speed 160 feet with a dashing barbarian, but a rogue can double dash it to 240 feet—why, because of wording? Yes, I would like it to be more consistent. Inconsistency still helps to sell the next book—buyer's hope for 'fixed' rules. Discussion and inconsistency is good for the business.

Nevertheless I can appreciate the efforts of the developers to create a usable system for fantasy role play. I'm just missing the storytelling from the dawn of rpg. Storytelling becomes impossible when players debate the wordings in the rules instead of using common sense what this rule shall do for the story. When have you used common sense last time to interpret the rules by meaning instead by wording?

This Sage Advice may clarify things:

https://www.sageadvice.eu/2018/04/03/does-warlock-devils-sight-see-in-darkness-as-if-it-were-dim-light-or-as-if-it-were-bright-light/