In Alberta, it goes something like this for the Mounties.. I'm sure I will be corrected on any that are out of date..
A - Rural (i.e. 'out in the country')
B - Town (i.e. bustling downtown Cochrane, Strathmore, Red Deer, etc)
C - Highway Patrol
D - Support
E - Investigations
F - Unknown (last I heard this was high ranking officers, I think)
G - Freeway Patrol (generally Hwy 2 between Cgy & Edm)
Z - Command post (i.e. bus/motorhome/etc)
I'm 99% certain on A/B/C, although the way Cochrane runs their detachment (they're closest to me), pretty much any car will take any call.. I routinely see B cars way outside town working incidents with me. The rest will be, as I said, corrected forthwith by others, I'm sure.