horsewoman vs equestrian

horsewoman and equestrian both are nouns.

Word	Noun	Adjective	Verb	Adverb
horsewoman	Yes	No	No	No
equestrian	Yes	Yes	No	No

As nouns, equestrian is a hypernym of horsewoman; that is, equestrian is a word with a broader meaning than horsewoman:

Other hypernyms of horsewoman include horseback rider, adult female, woman.

horsewoman (noun)	equestrian (noun)
a woman horseman	a person skilled in equitation

horsewoman (adjective)	equestrian (adjective)
	of or relating to or featuring horseback riding
	of or relating to or composed of knights