life belt vs seat belt

life belt and seat belt both are nouns.

Word	Noun	Adjective	Verb	Adverb
life belt	Yes	No	No	No
seat belt	Yes	No	No	No

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

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

Other hyponyms of life belt include seatbelt.

life belt (noun)	seat belt (noun)
a life preserver in the form of a ring of buoyant material	a safety belt used in a car or plane to hold you in your seat in case of an accident
belt attaching you to some object as a restraint in order to prevent you from getting hurt