posterior vs hindquarters

posterior and hindquarters both are nouns.

Word	Noun	Adjective	Verb	Adverb
posterior	Yes	Yes	No	No
hindquarters	Yes	No	No	No

As nouns, posterior and hindquarters are synonyms defined as:

posterior and hindquarters: the fleshy part of the human body that you sit on

posterior (noun)	hindquarters (noun)
the fleshy part of the human body that you sit on	the part of an animal that corresponds to the human buttocks
a tooth situated at the back of the mouth	the fleshy part of the human body that you sit on

posterior (adjective)	hindquarters (adjective)
located at or near or behind a part or near the end of a structure
coming at a subsequent time or stage