orca vs killer

orca and killer both are nouns.

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

As nouns, orca and killer are synonyms defined as:

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

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

orca (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