Bren vs submachine gun

Bren and submachine gun both are nouns.

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

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

Bren: a submachine gun operated by gas pressure; used by the British in World War II
submachine gun: machine gun that is a portable automatic firearm

Bren (noun)	submachine gun (noun)
a submachine gun operated by gas pressure; used by the British in World War II	machine gun that is a portable automatic firearm