webpage vs homepage

webpage and homepage both are nouns.

Word	Noun	Adjective	Verb	Adverb
webpage	Yes	No	No	No
homepage	Yes	No	No	No

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

webpage: a document connected to the World Wide Web and viewable by anyone connected to the internet who has a web browser
homepage: the opening page of a web site; also, the first page opened when a web browser is launched (default or start-up page)

Other hyponyms of webpage include home page.

webpage (noun)	homepage (noun)
a document connected to the World Wide Web and viewable by anyone connected to the internet who has a web browser	the opening page of a web site; also, the first page opened when a web browser is launched (default or start-up page)