raft vs life raft

raft and life raft both are nouns.

Word	Noun	Adjective	Verb	Adverb
raft	Yes	No	Yes	No
life raft	Yes	No	No	No

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

raft: a flat float (usually made of logs or planks) that can be used for transport or as a platform for swimmers
life raft: a raft to use if a ship must be abandoned in an emergency

Other hyponyms of raft include balsa raft, Kon Tiki, Carling float.

raft (noun)	life raft (noun)
a flat float (usually made of logs or planks) that can be used for transport or as a platform for swimmers	a raft to use if a ship must be abandoned in an emergency
a foundation (usually on soft ground) consisting of an extended layer of reinforced concrete
(often followed by `of') a large number or amount or extent