tussock vs coma

tussock and coma both are nouns.

Word	Noun	Adjective	Verb	Adverb
tussock	Yes	No	No	No
coma	Yes	No	No	No

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

tussock: a bunch of hair or feathers or growing grass
coma: (botany) a usually terminal tuft of bracts (as in the pineapple) or tuft of hairs (especially on certain seeds)

Other hyponyms of tussock include wisp, hexenbesen, staghead, witch broom, witches' broom.

tussock (noun)	coma (noun)
a bunch of hair or feathers or growing grass	a state of deep and often prolonged unconsciousness; usually the result of disease or injury
	(astronomy) the luminous cloud of particles surrounding the frozen nucleus of a comet; forms as the comet approaches the sun and is warmed
	(botany) a usually terminal tuft of bracts (as in the pineapple) or tuft of hairs (especially on certain seeds)