Brobdingnag vs mythical place

Brobdingnag and mythical place both are nouns.

Word	Noun	Adjective	Verb	Adverb
Brobdingnag	Yes	No	No	No
mythical place	Yes	No	No	No

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

Brobdingnag: a land imagined by Jonathan Swift where everything was enormous
mythical place: a place that exists only in imagination; a place said to exist in fictional or religious writings

Other hypernyms of Brobdingnag include fictitious place, imaginary place.

Brobdingnag (noun)	mythical place (noun)
a land imagined by Jonathan Swift where everything was enormous	a place that exists only in imagination; a place said to exist in fictional or religious writings