For what this may be worth to you, I believe that the first one is a rheostat pedal while the second one is electronic. The rheostat one is has an all metal case and it is mechanical, it has a coil of wire and a metal contact that swings across the coils when you press the pedal. The coils on mine are set in a ceramic block. It happens that I like that type of pedal, it's very old technology and it works very well for me. That said, they do get warm and people find that the electronic ones may provide more control.
Electronic pedals are generally plastic. and they don't get warm and if properly adjusted, will provide fine control.