submersible vs sub

submersible and sub both are nouns.

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

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

Other hyponyms of submersible include pigboat, submarine.

submersible (noun)	sub (noun)
a warship designed to operate under water	a submersible warship usually armed with torpedoes
an apparatus intended for use under water	a large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States

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

submersible (verb)	sub (verb)
	be a substitute