Viper 5000 Immobilizer vs Failsafe

Can someone explain the difference between the built in relay of the Immobilizer vs. the additional output for the Failsafe starter kill relay. I read in the manual that the VRS feature requires the failsafe to be wired & programmed. So my take is that the immobilizer is the alarm's "normal" starter kill when armed and the failsafe is for the VRS.

Would they be wired in series as such: ignition lead through the NC of the immobilizer then through the failsafe relay's NC and on to the starter?

There will be more questions about the 5000 I'm sure as I am having one installed into the wife's 85" Regal that was recently stolen & recovered.

Thanks for the help, Steve