submersible vs pigboat

submersible and pigboat both are nouns.

Word	Noun	Adjective	Verb	Adverb
submersible	Yes	Yes	No	No
pigboat	Yes	No	No	No

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

Other hyponyms of submersible include sub, submarine.

submersible (noun)	pigboat (noun)
a warship designed to operate under water	a submersible warship usually armed with torpedoes
an apparatus intended for use under water

submersible (adjective)	pigboat (adjective)
capable of being immersed in water or functioning while submerged