sneak thief vs thief

sneak thief and thief both are nouns.

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

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

sneak thief: a thief who steals without using violence
thief: a criminal who takes property belonging to someone else with the intention of keeping it or selling it

Other hypernyms of sneak thief include stealer.

sneak thief (noun)	thief (noun)
a thief who steals without using violence	a criminal who takes property belonging to someone else with the intention of keeping it or selling it