Passenger Tires vs Light Truck Tires: what's the difference?

Tougher with a higher payload rating normally on the LTs. Passenger tires will be more pliable with a smoother ride and have a lower payload rating.

If you tow with any regularity, get the LTs.

Then your good to go with the passengers.

Most truck sizes come in one or the other

I don't think there are many sizes where you can choose LT or P, usually the size you pick determines that.