boater vs gondolier

boater and gondolier both are nouns.

Word	Noun	Adjective	Verb	Adverb
boater	Yes	No	No	No
gondolier	Yes	No	No	No

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

Other hyponyms of boater include canoeist, paddler, ferryman, gondoliere, rower, punter.

boater (noun)	gondolier (noun)
a stiff hat made of straw with a flat crown	a (Venetian) boatman who propels a gondola
someone who drives or rides in a boat