burglar vs stealer

burglar and stealer both are nouns.

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

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

burglar: a thief who enters a building with intent to steal
stealer: a criminal who takes property belonging to someone else with the intention of keeping it or selling it

Other hypernyms of burglar include thief.

burglar (noun)	stealer (noun)
a thief who enters a building with intent to steal	a criminal who takes property belonging to someone else with the intention of keeping it or selling it