watercourse vs headrace

watercourse and headrace both are nouns.

Word	Noun	Adjective	Verb	Adverb
watercourse	Yes	No	No	No
headrace	Yes	No	No	No

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

Other hyponyms of watercourse include canal, flume, tailrace.

watercourse (noun)	headrace (noun)
a conduit through which water flows	a waterway that feeds water to a mill or water wheel or turbine
a natural body of running water flowing on or under the earth
natural or artificial channel through which water flows