Bofors gun vs pom-pom

Bofors gun and pom-pom both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bofors gun	Yes	No	No	No
pom-pom	Yes	No	No	No

As nouns, pom-pom is a hypernym of Bofors gun; that is, pom-pom is a word with a broader meaning than Bofors gun:

Other hypernyms of Bofors gun include ack-ack, ack-ack gun, antiaircraft, antiaircraft gun, flack, flak.

Bofors gun (noun)	pom-pom (noun)
an automatic double-barreled antiaircraft gun	artillery designed to shoot upward at airplanes
	decoration consisting of a ball of tufted wool or silk; usually worn on a hat