in my search for a new radiator I'm seeing that there is an option for "heavy duty cooling". Is this referring to an option on the vehicle or is this simply referring to a radiator with an extra row of coils?

 

Both. The larger, higher capacity vehicles generally have a larger radiator like what you described in it.

If you're thinking of retrofitting a larger radiator to your vehicle, compare it with the original first to be sure it will fit.