militia vs trainband

militia and trainband both are nouns.

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

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

militia: civilians trained as soldiers but not part of the regular army
trainband: a company of militia in England or America from the 16th century to the 18th century

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

militia (noun)	trainband (noun)
civilians trained as soldiers but not part of the regular army	a company of militia in England or America from the 16th century to the 18th century
the entire body of physically fit civilians eligible by law for military service