em vs em quad

em and em quad both are nouns.

Word	Noun	Adjective	Verb	Adverb
em	Yes	No	No	No
em quad	Yes	No	No	No

As nouns, em and em quad are synonyms defined as:

Other synonyms of em include mutton quad.

em (noun)	em quad (noun)
a quad with a square body	a quad with a square body
a linear unit (1/6 inch) used in printing