gecko vs flying gecko

gecko and flying gecko both are nouns.

Word	Noun	Adjective	Verb	Adverb
gecko	Yes	No	No	No
flying gecko	Yes	No	No	No

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

gecko: any of various small chiefly tropical and usually nocturnal insectivorous terrestrial lizards typically with immovable eyelids; completely harmless
flying gecko: a gecko that has membranous expansions along the sides of its body and limbs and tail that enable it to glide short distances

Other hyponyms of gecko include fringed gecko, Ptychozoon homalocephalum, banded gecko.

gecko (noun)	flying gecko (noun)
any of various small chiefly tropical and usually nocturnal insectivorous terrestrial lizards typically with immovable eyelids; completely harmless	a gecko that has membranous expansions along the sides of its body and limbs and tail that enable it to glide short distances