web page vs text file

web page and text file both are nouns.

Word	Noun	Adjective	Verb	Adverb
web page	Yes	No	No	No
text file	Yes	No	No	No

As nouns, text file is a hypernym of web page; that is, text file is a word with a broader meaning than web page:

web page: a document connected to the World Wide Web and viewable by anyone connected to the internet who has a web browser
text file: (computer science) a computer file that contains text (and possibly formatting instructions) using seven-bit ASCII characters

Other hypernyms of web page include document.

web page (noun)	text file (noun)
a document connected to the World Wide Web and viewable by anyone connected to the internet who has a web browser	(computer science) a computer file that contains text (and possibly formatting instructions) using seven-bit ASCII characters