microscope slide vs plate glass

microscope slide and plate glass both are nouns.

Word	Noun	Adjective	Verb	Adverb
microscope slide	Yes	No	No	No
plate glass	Yes	No	No	No

As nouns, plate glass is a hypernym of microscope slide; that is, plate glass is a word with a broader meaning than microscope slide:

microscope slide: a small flat rectangular piece of glass on which specimens can be mounted for microscopic study
plate glass: glass formed into large thin sheets

Other hypernyms of microscope slide include sheet glass.

microscope slide (noun)	plate glass (noun)
a small flat rectangular piece of glass on which specimens can be mounted for microscopic study	glass formed into large thin sheets