pustule vs pimple

pustule and pimple both are nouns.

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

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

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

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

pustule (noun)	pimple (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