I am surprised that the Canadian English block is so large. Having lived in both places, there is a definite difference in accent between Western Canada and Southern Ontario.
EDIT: The stereotypical "out" and "about" pronunciation is much more prominent in Southern Ontario.
Actually the 'aboot' thing that people stereotype about Canadians is more prominent in the upper midwest US than it is in most parts of Canada.
I do hear a difference between western Canada and Ontario (I'm from the former and live in the latter.) But there's also a known dialect difference between central and southern Alberta (former settled by English/Ukrainian/Germans the other by American immigrants).
When i am in the us everyone thinks im from california. Regardless of studies, BC, cali and alaska share a west coast accent. Thats one of the reasons hollywood likes to film in vancouver.
EDIT: The stereotypical "out" and "about" pronunciation is much more prominent in Southern Ontario.