apparatus vs body part

apparatus and body part both are nouns.

Word	Noun	Adjective	Verb	Adverb
apparatus	Yes	No	No	No
body part	Yes	No	No	No

As nouns, body part is a hypernym of apparatus; that is, body part is a word with a broader meaning than apparatus:

apparatus: (anatomy) a group of body parts that work together to perform a given function
body part: any part of an organism such as an organ or extremity

apparatus (noun)	body part (noun)
equipment designed to serve a specific function	any part of an organism such as an organ or extremity
(anatomy) a group of body parts that work together to perform a given function