Has anyone tried simulating a particular circuit in both Hspice and MATLAB Simulink ? How do the results compare ?

I tried to simulate a phase locked loop circuit in Hspice and then in MATLAB. When I simulated the PLL, designed in Hspice, in Simulink, I copied the parameters such as lpf transfer function, vco input sensitivity, vco quiscent frequency of the Hspice circuits onto the blocks in Simulink. Yet the capture range was very different from what I got from Hspice simulation. Does anyone know why this happens ?