drill bit vs drilling bit

drill bit and drilling bit both are nouns.

Word	Noun	Adjective	Verb	Adverb
drill bit	Yes	No	No	No
drilling bit	Yes	No	No	No

As nouns, drill bit and drilling bit are synonyms defined as:

drill bit (noun)	drilling bit (noun)
a bit used in drilling for oil	a bit used in drilling for oil