"While wearing this amulet, you are hidden from divination magic. You can't be targeted by such magic or perceived through magical scrying sensors."

Isn't detect thoughts a divination spell? So then, wouldn't this amulet work the same as a ring of mind-shielding? If so, what's the point of ever having a ring of mind-shielding instead of an amulet that does what the ring does and more?

The target of Detect Thoughts is Self. 

It also doesn't prevent divination being cast upon you when used generally. It just means you are hidden from it. Spells can't detect your presence, find where you are, see you, or such things.

But if a person with Detect Thoughts could see you without magic - they can use the ability granted by the spell on you and read your thoughts. 

Also, a person with a feature that does something similar or can speak using telepathy can use those on you (but the Ring of Mind Shielding would protect from those).

The wearer of an Amulet of Proof against Detection and Location is hidden from divination magic such as detect thoughts .