wind generator vs windmill

wind generator and windmill both are nouns.

Word	Noun	Adjective	Verb	Adverb
wind generator	Yes	No	No	No
windmill	Yes	No	No	No

As nouns, wind generator and windmill are synonyms defined as:

wind generator and windmill: generator that extracts usable energy from winds

Other synonyms of wind generator include aerogenerator.

wind generator (noun)	windmill (noun)
generator that extracts usable energy from winds	generator that extracts usable energy from winds
	a mill that is powered by the wind