During development with Wind River Workbench, I use VxWorks Simulator to test code. I also heard of Simics is a virtual environment which can run VxWorks. Are Simics and VxWorks Simulator the same thing?
They are 2 different products.
VxSim is bundled with the vxWorks development environment and provides a simple x86 virtual board with memory, a serial port and possibly a network connection. You can not simulate real devices like A/D, PCI devices, etc... in vxSim
Simics in comparison is an actual system simulation environment, where an entire hardware platform is emulated, including CPU, hardware devices (PCI bus, A/D converters, FPGA, etc...) and it can run the exact same binary as the real board would.
Simics is also not restricted to vxWorks. A simics simulation could run any software: Windows, Linux, other OSes.