walrus vs sea horse

walrus and sea horse both are nouns.

Word	Noun	Adjective	Verb	Adverb
walrus	Yes	No	No	No
sea horse	Yes	No	No	No

As nouns, walrus and sea horse are synonyms defined as:

walrus and sea horse: either of two large northern marine mammals having ivory tusks and tough hide over thick blubber

Other synonyms of walrus include seahorse.

walrus (noun)	sea horse (noun)
either of two large northern marine mammals having ivory tusks and tough hide over thick blubber	small fish with horse-like heads bent sharply downward and curled tails; swim in upright position
	either of two large northern marine mammals having ivory tusks and tough hide over thick blubber