What's the basic difference between a Light Truck and a Passenger tire?

I'm planning to replace my stock passenger tires on the truck and not sure what the real difference is between a 31" LT and a 31" P tire.

Thanks

 

i am guessing it has to do with load rating, not sure probably varies from tire to tire also.

 

The LT tires are more heavily constructed. When used on a truck a passenger tire has to be de-rated by 10%.

 

Usually there is at least one extra cord in the side wall and the rubber is thicker in the sidewall. On LT tires there is less sidewall flex and the tires tend to be rated far above the P metric tires. P metric tires off-road tend to have their sidewalls cut easily. Worse tires I have seen for this are the Wilderness AT tires.