For the Infantry....
Reg to Reserve: Everything counts, but what rank they make you depends on their needs - ie, they may not need another sergeant major or Colonel. But Reserve units are usualy anxious to take advantage of Reg Force experience.
Reserve to Reg: Your time in counts towads your pension. Other than that, it matters jack ****. If you get a Reg course - like Jump, and last summer‘s Recce course was Reg Force - it still counts, but Militia courses don‘t.
If you go on a tour your not allowed to go to Battle School, you go strait to Regiment.
If you have massive amounts of time in and experience you might get to keep some rank. For example, my QL3 instructor, a sergeant with a tour in the Golan and lots of time in, transferred over and became a corporal.