sluice valve vs floodgate

sluice valve and floodgate both are nouns.

Word	Noun	Adjective	Verb	Adverb
sluice valve	Yes	No	No	No
floodgate	Yes	No	No	No

As nouns, sluice valve and floodgate are synonyms defined as:

sluice valve and floodgate: regulator consisting of a valve or gate that controls the rate of water flow through a sluice

Other synonyms of sluice valve include head gate, penstock, sluicegate, water gate.

sluice valve (noun)	floodgate (noun)
regulator consisting of a valve or gate that controls the rate of water flow through a sluice	regulator consisting of a valve or gate that controls the rate of water flow through a sluice
	something that restrains a flood or outpouring