lifesaver vs lifeguard

lifesaver and lifeguard both are nouns.

Word	Noun	Adjective	Verb	Adverb
lifesaver	Yes	No	No	No
lifeguard	Yes	No	No	No

As nouns, lifesaver and lifeguard are synonyms defined as:

lifesaver and lifeguard: an attendant employed at a beach or pool to protect swimmers from accidents

lifesaver (noun)	lifeguard (noun)
a life preserver in the form of a ring of buoyant material	an attendant employed at a beach or pool to protect swimmers from accidents
an attendant employed at a beach or pool to protect swimmers from accidents