body snatcher vs thief

body snatcher and thief both are nouns.

Word	Noun	Adjective	Verb	Adverb
body snatcher	Yes	No	No	No
thief	Yes	No	No	No

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

body snatcher: someone who takes bodies from graves and sells them for anatomical dissection
thief: a criminal who takes property belonging to someone else with the intention of keeping it or selling it

Other hypernyms of body snatcher include stealer.

body snatcher (noun)	thief (noun)
someone who takes bodies from graves and sells them for anatomical dissection	a criminal who takes property belonging to someone else with the intention of keeping it or selling it