aquanaut vs natator

aquanaut and natator both are nouns.

Word	Noun	Adjective	Verb	Adverb
aquanaut	Yes	No	No	No
natator	Yes	No	No	No

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

aquanaut: an underwater swimmer equipped with a face mask and foot fins and either a snorkel or an air cylinder
natator: a person who travels through the water by swimming

Other hypernyms of aquanaut include bather, swimmer.

aquanaut (noun)	natator (noun)
an underwater swimmer equipped with a face mask and foot fins and either a snorkel or an air cylinder	a person who travels through the water by swimming
a skilled worker who can live in underwater installations and participate in scientific research