rudiment vs body part

rudiment and body part both are nouns.

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

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

rudiment: the remains of a body part that was functional at an earlier stage of life
body part: any part of an organism such as an organ or extremity

rudiment (noun)	body part (noun)
the remains of a body part that was functional at an earlier stage of life	any part of an organism such as an organ or extremity