In general, what are the RPM ranges/differences between the various compression stages on a 2 or 3 spool (LP,IP,HP) turbojet/fan engine?
RPM does not generally fluctuate in flight, or on the ground for that matter.
For 'fan' RPM, 100% N1, is somewhere between 2000 to 4000.(aka LP stage)
For 'core' RPM, 100% N2, is somewhere between 9000 to 14000.(HP stage)
The 3rd spool (IP stage) RPM would be in between the LP and HP nominally around 7000.
These are ballpark figures.