seaplane vs floatplane

seaplane and floatplane both are nouns.

Word	Noun	Adjective	Verb	Adverb
seaplane	Yes	No	Yes	No
floatplane	Yes	No	No	No

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

seaplane: an airplane that can land on or take off from water
floatplane: a seaplane equipped with pontoons for landing or taking off from water

Other hyponyms of seaplane include pontoon plane, flying boat.

seaplane (noun)	floatplane (noun)
an airplane that can land on or take off from water	a seaplane equipped with pontoons for landing or taking off from water

seaplane (verb)	floatplane (verb)
glide on the water in a hydroplane