Sten gun vs submachine gun

Sten gun and submachine gun both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sten gun	Yes	No	No	No
submachine gun	Yes	No	No	No

As nouns, submachine gun is a hypernym of Sten gun; that is, submachine gun is a word with a broader meaning than Sten gun:

Sten gun (noun)	submachine gun (noun)
a lightweight British submachine gun	machine gun that is a portable automatic firearm