What is the difference between a "tractor-trailer" and "truck-trailer"?

I did just that and learned something I did not know. This is in 390.5.

Trailer includes:

(1) Full trailer means any motor vehicle other than a pole trailer which is designed to be drawn by another motor vehicle and so constructed that no part of its weight, except for the towing device, rests upon the self-propelled towing motor vehicle. A semitrailer equipped with an auxiliary front axle (converter dolly) shall be considered a full trailer.

(2) Pole trailer means any motor vehicle which is designed to be drawn by another motor vehicle and attached to the towing motor vehicle by means of a “reach” or “pole,” or by being “boomed” or otherwise secured to the towing motor vehicle, for transporting long or irregularly shaped loads such as poles, pipes, or structural members, which generally are capable of sustaining themselves as beams between the supporting connections.

(3) Semitrailer means any motor vehicle, other than a pole trailer, which is designed to be drawn by another motor vehicle and is constructed so that some part of its weight rests upon the self-propelled towing motor vehicle.


So based on that definition, there is a difference. HOWEVER, I think @Ridgeline nailed it. People use these terms interchangeably today.

 

truck and full trailer combo. Out west this setup ruled for decades because more could be hauled in the length allowed.