It is hard to discuss about screenshots. Here are two obvious differences:
The resistor R7 in your SPICE schematic has a value of 130kΩ - the corresponding resistor in your PLECS model (called R6) has a value of 10kΩ.You write that your SPICE model uses diodes with a forward voltage of 500mV - the diodes in your PLECS model have a forward voltage of 1V.Besides, it is not clear to me that the Op-Amp circuit in your PLECS schematic is really equivalent to the controlled voltage source in your SPICE schematic. (Did you know that PLECS also has a controlled voltage source?)