looking glass vs mirror

looking glass and mirror both are nouns.

Word	Noun	Adjective	Verb	Adverb
looking glass	Yes	No	No	No
mirror	Yes	No	Yes	No

As nouns, mirror is a hypernym of looking glass; that is, mirror is a word with a broader meaning than looking glass:

looking glass (noun)	mirror (noun)
a mirror; usually a ladies' dressing mirror	polished surface that forms images by reflecting light
	a faithful depiction or reflection

looking glass (verb)	mirror (verb)
	reflect or resemble
	reflect as if in a mirror