urate vs tophus

urate and tophus both are nouns.

Word	Noun	Adjective	Verb	Adverb
urate	Yes	No	No	No
tophus	Yes	No	No	No

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

urate: a salt of uric acid
tophus: a deposit of urates around a joint or in the external ear; diagnostic of advanced or chronic gout

Other hyponyms of urate include chalkstone.

urate (noun)	tophus (noun)
a salt of uric acid	an incrustation that forms on the teeth and gums
	a deposit of urates around a joint or in the external ear; diagnostic of advanced or chronic gout