water gate vs sluice valve

water gate and sluice valve both are nouns.

Word	Noun	Adjective	Verb	Adverb
water gate	Yes	No	No	No
sluice valve	Yes	No	No	No

As nouns, water gate and sluice valve are synonyms defined as:

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

Other synonyms of water gate include floodgate, head gate, penstock, sluicegate.

water gate (noun)	sluice valve (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