amphibia vs amphibian

amphibia and amphibian both are nouns.

Word	Noun	Adjective	Verb	Adverb
amphibia	Yes	No	No	No
amphibian	Yes	Yes	No	No

amphibia (noun)	amphibian (noun)
the class of vertebrates that live on land but breed in water, frogs, toads, newts, salamanders, caecilians	cold-blooded vertebrate typically living on land but breeding in water; aquatic larvae undergo metamorphosis into adult form
	an airplane designed to take off and land on water
	a flat-bottomed motor vehicle that can travel on land or water

amphibia (adjective)	amphibian (adjective)
	relating to or characteristic of animals of the class Amphibia