tidewater stream vs watercourse

tidewater stream and watercourse both are nouns.

Word	Noun	Adjective	Verb	Adverb
tidewater stream	Yes	No	No	No
watercourse	Yes	No	No	No

As nouns, watercourse is a hypernym of tidewater stream; that is, watercourse is a word with a broader meaning than tidewater stream:

tidewater stream: a stream in which the effects of the tide extend far upstream
watercourse: a natural body of running water flowing on or under the earth

Other hypernyms of tidewater stream include stream.

tidewater stream (noun)	watercourse (noun)
a stream in which the effects of the tide extend far upstream	a conduit through which water flows
	a natural body of running water flowing on or under the earth
	natural or artificial channel through which water flows