burglar vs thief

burglar and thief both are nouns.

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

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

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

Other hypernyms of burglar include stealer.

burglar (noun)	thief (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