window glass vs pane of glass

window glass and pane of glass both are nouns.

Word	Noun	Adjective	Verb	Adverb
window glass	Yes	No	No	No
pane of glass	Yes	No	No	No

As nouns, window glass and pane of glass are synonyms defined as:

window glass and pane of glass: sheet glass cut in shapes for windows or doors

Other synonyms of window glass include pane.

window glass (noun)	pane of glass (noun)
sheet glass cut in shapes for windows or doors	sheet glass cut in shapes for windows or doors