chest vs external body part

chest and external body part both are nouns.

Word	Noun	Adjective	Verb	Adverb
chest	Yes	No	No	No
external body part	Yes	No	No	No

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

chest (noun)	external body part (noun)
box with a lid; used for storage; usually large and sturdy	any body part visible externally
furniture with drawers for keeping clothes
the part of the human torso between the neck and the diaphragm or the corresponding part in other vertebrates
the front of the trunk from the neck to the abdomen