confluent vs tributary

confluent and tributary both are nouns.

Word	Noun	Adjective	Verb	Adverb
confluent	Yes	Yes	No	No
tributary	Yes	Yes	No	No

As nouns, confluent and tributary are synonyms defined as:

Other synonyms of confluent include affluent, feeder.

confluent (noun)	tributary (noun)
a branch that flows into the main stream	a branch that flows into the main stream

confluent (adjective)	tributary (adjective)
flowing together	tending to bring about; being partly responsible for
	paying tribute
	(of a stream) flowing into a larger stream