trucking rig vs tractor trailer

trucking rig and tractor trailer both are nouns.

Word	Noun	Adjective	Verb	Adverb
trucking rig	Yes	No	No	No
tractor trailer	Yes	No	No	No

As nouns, trucking rig and tractor trailer are synonyms defined as:

trucking rig and tractor trailer: a truck consisting of a tractor and trailer together

Other synonyms of trucking rig include articulated lorry, rig, semi, trailer truck.

trucking rig (noun)	tractor trailer (noun)
a truck consisting of a tractor and trailer together	a truck consisting of a tractor and trailer together