clustering vs tussock

clustering and tussock both are nouns.

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

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

Other hyponyms of clustering include knot, swad, tuft.

clustering (noun)	tussock (noun)
a grouping of a number of similar things	a bunch of hair or feathers or growing grass