You are no mere skeleton or corpse and other undead can tell. Undead can tell you are one of them and if you are stronger than them, unless attacked or ordered to, undead won’t attack you.

You can absorb the souls of the dead, and they invigorate you. You can harvest up to half your level (rounded down) in souls from the dead that are within 60 feet of you and regain 5 hit point for every soul. This ability takes 1 minute per soul. You do not fully destroy a creatures soul and so they can still be resurrected after this feature though it can not be done within 24 hours of the creatures soul being eaten. Once you use this feature, you can't do so again until you finish a short or long rest

You do not require air, food, drink, or sleep. You gain immunity to poison damage and the poisoned condition. Health potions have no effect on you though healing spells still work, though healing received is halved for any spell that says it doesn’t effect undead.

Your Charisma, and Wisdom scores each increase by 2, and your your Strength score decreases by 2.

You give off a unsettling aura in a 5 foot radius round you. If a creature comes in physical contact with you (melee or grappled) then the creature must make a Wisdom saving throw. If it fails then the creature becomes frightened. On a successful save the creature can't be frightened by you and nothing happens.

This only affects living creatures and not Undead or Constructs.