sneak thief vs pilferer

sneak thief and pilferer both are nouns.

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

As nouns, sneak thief and pilferer are synonyms defined as:

Other synonyms of sneak thief include snitcher.

sneak thief (noun)	pilferer (noun)
a thief who steals without using violence	a thief who steals without using violence