a table of comparisons would be nice.
here will get you started
same
both can be controlled by your phone
both can act as either a FPP remote or master
both can be configured through a web page
differences
rpi can drive 250K channels, laptop can drive over 1 million
rpm (sep zero) uses way less power. rpi good for battery operation of scheduler
more external interfaces available for rpi than for laptop. all of those plugin boards that give you relays, A to D, cameras, ultrasonic sensors .etc.
do you want to tie up a rpi for 2 months or a laptop?
features only on xschedule
ability to map live video directly onto your megatree or matrix
it used to be that the scheduler in xLights (written in 2010) was way less capable than FPP on a rpi.
Over the last year, xScheduler now has more features. FPP group is now working to close that gap.
others can add to this list