sea animal vs marine creature

sea animal and marine creature both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea animal	Yes	No	No	No
marine creature	Yes	No	No	No

As nouns, sea animal and marine creature are synonyms defined as:

sea animal and marine creature: any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals

Other synonyms of sea animal include marine animal, sea creature.

sea animal (noun)	marine creature (noun)
any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals	any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals