lifter vs stealer

lifter and stealer both are nouns.

Word	Noun	Adjective	Verb	Adverb
lifter	Yes	No	No	No
stealer	Yes	No	No	No

As nouns, stealer is a hypernym of lifter; that is, stealer is a word with a broader meaning than lifter:

lifter: a thief who steals goods that are in a store
stealer: a criminal who takes property belonging to someone else with the intention of keeping it or selling it

Other hypernyms of lifter include thief.

lifter (noun)	stealer (noun)
an athlete who lifts barbells	a criminal who takes property belonging to someone else with the intention of keeping it or selling it
a thief who steals goods that are in a store