Request Stop is related to the IsStopRequested() function that can be used in a Decision stage. By default the function returnes False, but when the control room user issues the Request Stop command, the output of the function changes to True. This enables the process designer to create a pathway based on IsStopRequested() that allows the process to gracefully come to an early end. By contrast, Immediate Stop is what it sounds like - a brutal command to stop right now, regardless of what the process is currently doing.
