militia vs SA

militia and SA both are nouns.

Word	Noun	Adjective	Verb	Adverb
militia	Yes	No	No	No
SA	Yes	No	No	No

As nouns, SA is a hyponym of militia; that is, SA is a word with a more specific, narrower meaning than militia:

militia: civilians trained as soldiers but not part of the regular army
SA: Nazi militia created by Hitler in 1921 that helped him to power but was eclipsed by the SS after 1943

Other hyponyms of militia include Storm Troops, Sturmabteilung, trainband.

militia (noun)	SA (noun)
civilians trained as soldiers but not part of the regular army	Nazi militia created by Hitler in 1921 that helped him to power but was eclipsed by the SS after 1943
the entire body of physically fit civilians eligible by law for military service