torso vs body part

torso and body part both are nouns.

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

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

torso (noun)	body part (noun)
the body excluding the head and neck and limbs	any part of an organism such as an organ or extremity