1.  lifesaver(n = noun.person) lifeguard - an attendant employed at a beach or pool to protect swimmers from accidents;
is a kind of attendant, attender, tender

2.  lifesaver(n = noun.artifact) life belt, life buoy, life ring - a life preserver in the form of a ring of buoyant material;
is a kind of flotation device, life preserver, preserver
has particulars: breeches buoy