OrCAD doesn't yields same result for this difference amplifier
With the input voltages present, the output would need to be -24 volts but, it's likely that the power rails applied in OrCAD are limiting the output to +/- 15 volts hence, you get negative clipping.
Try inputting 0.6 volts and 0.2 volts to get -2.4 volts on the output.