Reserve MPs have the same arresting powers as a bloke working at 7-11. A Citizen‘s arrest.
Regular Force MPs have ‘peace officer status‘ and arresting powers Canada wide, and are classed as ‘police officers‘, having the same powers of arrest as RCMP and regional/city police. At least it was like that 10 yrs ago, and I cant see that changing.
Regular Force Military Police also have a badge with a number too, similar to the RCMP.
So, there is a big difference.
Reserve Military police do have a role, and it can range from establishing PW cages, to marking routes for convoys, but in reality these are common duties to both Regular and Reserve MPs.
MPs have many roles besides the power of arrest.
I think the only lophole may be when a Reserve MP gets onto a ‘Class C callout‘( not a class B or Class B ‘A‘). This may change his status but only for the duraction of teh Class C, again i might be wrong here.
Cheers,
Wes