life buoy vs saver

life buoy

noun
  • Something that rescues one from difficulties. 

  • A buoyant object (most commonly torus-shaped) that is used as a life-saving device by keeping a person afloat. 

saver

noun
  • One who saves. 

  • A ticket or coupon that offers a discount. 

  • One who keeps savings more than usual. 

How often have the words life buoy and saver occurred in a corpus of books? (source: Google Ngram Viewer )