killer whale vs killer

killer whale and killer both are nouns.

Word	Noun	Adjective	Verb	Adverb
killer whale	Yes	No	No	No
killer	Yes	No	No	No

As nouns, killer whale and killer are synonyms defined as:

killer whale and killer: predatory black-and-white toothed whale with large dorsal fin; common in cold seas

Other synonyms of killer whale include grampus, orca, Orcinus orca, sea wolf.

killer whale (noun)	killer (noun)
predatory black-and-white toothed whale with large dorsal fin; common in cold seas	predatory black-and-white toothed whale with large dorsal fin; common in cold seas
	a difficulty that is hard to deal with
	someone who causes the death of a person or animal
	the causal agent resulting in death