safety belt vs seatbelt

safety belt and seatbelt both are nouns.

Word	Noun	Adjective	Verb	Adverb
safety belt	Yes	No	No	No
seatbelt	Yes	No	No	No

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

safety belt: belt attaching you to some object as a restraint in order to prevent you from getting hurt
seatbelt: a safety belt used in a car or plane to hold you in your seat in case of an accident

Other hyponyms of safety belt include seat belt.

safety belt (noun)	seatbelt (noun)
belt attaching you to some object as a restraint in order to prevent you from getting hurt	a safety belt used in a car or plane to hold you in your seat in case of an accident