Exit and resume on reboot will, on detection of an impending reboot, exit the installation after setting itself to be launched on startup. Then presumably the prerequisite will have kicked off a reboot, so the machine will restart, and the setup will be launched. However if the prerequisite did not restart the machine, the setup will just disappear.
Reboot the machine and resume on reboot will, in the same scenario, reboot the machine itself. It will still exit after setting itself to be launched on startup, but it will not depend on the prerequisite to restart the machine.
