pontoon vs barge

pontoon and barge both are nouns.

Word	Noun	Adjective	Verb	Adverb
pontoon	Yes	No	No	No
barge	Yes	No	Yes	No

As nouns, barge is a hypernym of pontoon; that is, barge is a word with a broader meaning than pontoon:

pontoon: (nautical) a floating structure (as a flat-bottomed boat) that serves as a dock or to support a bridge
barge: a flatbottom boat for carrying heavy loads (especially on canals)

Other hypernyms of pontoon include flatboat, hoy, lighter.

pontoon (noun)	barge (noun)
a float supporting a seaplane	a flatbottom boat for carrying heavy loads (especially on canals)
(nautical) a floating structure (as a flat-bottomed boat) that serves as a dock or to support a bridge

pontoon (verb)	barge (verb)
	push one's way
	transport by barge on a body of water