acne vs hickey

acne and hickey both are nouns.

Word	Noun	Adjective	Verb	Adverb
acne	Yes	No	No	No
hickey	Yes	No	No	No

As nouns, hickey is a hyponym of acne; that is, hickey is a word with a more specific, narrower meaning than acne:

acne: an inflammatory disease involving the sebaceous glands of the skin; characterized by papules or pustules or comedones
hickey: a small inflamed elevation of the skin; a pustule or papule; common symptom in acne

Other hyponyms of acne include acne rosacea, rosacea, acne vulgaris, pimple, zit.

acne (noun)	hickey (noun)
an inflammatory disease involving the sebaceous glands of the skin; characterized by papules or pustules or comedones	a temporary red mark on a person's skin resulting from kissing or sucking by their lover
	a small inflamed elevation of the skin; a pustule or papule; common symptom in acne