webpage vs web page

webpage and web page both are nouns.

Word	Noun	Adjective	Verb	Adverb
webpage	Yes	No	No	No
web page	Yes	No	No	No

As nouns, webpage and web page are synonyms defined as:

webpage and web page: a document connected to the World Wide Web and viewable by anyone connected to the internet who has a web browser

webpage (noun)	web page (noun)
a document connected to the World Wide Web and viewable by anyone connected to the internet who has a web browser	a document connected to the World Wide Web and viewable by anyone connected to the internet who has a web browser