safety device vs fender

safety device and fender both are nouns.

Word	Noun	Adjective	Verb	Adverb
safety device	Yes	No	No	No
fender	Yes	No	No	No

As nouns, fender is a hyponym of safety device; that is, fender is a word with a more specific, narrower meaning than safety device:

Other hyponyms of safety device include safety catch, safety lock.

safety device (noun)	fender (noun)
a device designed to prevent injury or accidents	a cushion-like device that reduces shock due to an impact
	a barrier that surrounds the wheels of a vehicle to block splashing water or mud
	a low metal guard to confine falling coals to a hearth
	an inclined metal frame at the front of a locomotive to clear the track