killer vs throttler

killer and throttler both are nouns.

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

As nouns, throttler is a hyponym of killer; that is, throttler is a word with a more specific, narrower meaning than killer:

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