pustule vs zit

pustule and zit both are nouns.

Word	Noun	Adjective	Verb	Adverb
pustule	Yes	No	No	No
zit	Yes	No	No	No

As nouns, zit is a hypernym of pustule; that is, zit is a word with a broader meaning than pustule:

pustule: a small inflamed elevation of skin containing pus; a blister filled with pus
zit: a small inflamed elevation of the skin; a pustule or papule; common symptom in acne

Other hypernyms of pustule include bleb, blister, bulla, hickey, pimple.

pustule (noun)	zit (noun)
a small inflamed elevation of skin containing pus; a blister filled with pus	a small inflamed elevation of the skin; a pustule or papule; common symptom in acne