drilling rig vs drill rig

drilling rig and drill rig both are nouns.

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

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

Other synonyms of drilling rig include oil rig, oilrig.

drilling rig (noun)	drill rig (noun)
rig used in drilling for oil or gas	rig used in drilling for oil or gas