aquanaut vs skilled workman

aquanaut and skilled workman both are nouns.

Word	Noun	Adjective	Verb	Adverb
aquanaut	Yes	No	No	No
skilled workman	Yes	No	No	No

As nouns, skilled workman is a hypernym of aquanaut; that is, skilled workman is a word with a broader meaning than aquanaut:

aquanaut: a skilled worker who can live in underwater installations and participate in scientific research
skilled workman: a worker who has acquired special skills

Other hypernyms of aquanaut include skilled worker, trained worker.

aquanaut (noun)	skilled workman (noun)
an underwater swimmer equipped with a face mask and foot fins and either a snorkel or an air cylinder	a worker who has acquired special skills
a skilled worker who can live in underwater installations and participate in scientific research