Atlantis vs fictitious place

Atlantis and fictitious place both are nouns.

Word	Noun	Adjective	Verb	Adverb
Atlantis	Yes	No	No	No
fictitious place	Yes	No	No	No

As nouns, fictitious place is a hypernym of Atlantis; that is, fictitious place is a word with a broader meaning than Atlantis:

Atlantis: according to legend, an island in the Atlantic Ocean that Plato said was swallowed by an earthquake
fictitious place: a place that exists only in imagination; a place said to exist in fictional or religious writings

Other hypernyms of Atlantis include imaginary place, mythical place.

Atlantis (noun)	fictitious place (noun)
according to legend, an island in the Atlantic Ocean that Plato said was swallowed by an earthquake	a place that exists only in imagination; a place said to exist in fictional or religious writings