motor horn vs hooter

motor horn and hooter both are nouns.

Word	Noun	Adjective	Verb	Adverb
motor horn	Yes	No	No	No
hooter	Yes	No	No	No

As nouns, motor horn and hooter are synonyms defined as:

motor horn and hooter: a device on an automobile for making a warning noise

Other synonyms of motor horn include automobile horn, car horn, horn.

motor horn (noun)	hooter (noun)
a device on an automobile for making a warning noise	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes
	a device on an automobile for making a warning noise
	informal terms for the nose