I am a canadian who transfered to BYU. I went to Mount royal for 1 semester. I didn't leave because I thought it would be easier but I was told by the college advisors at MRC that that my chances were better getting into a US dental school over a Canadian school. And they said that attending a US undergrad woiuld improve my chances even more.
In my opinion there are much easier schools than BYU, it is a tough program. However in general, the main differences between the US and Canada seem to be:
1 Grading on a curve is not as common in the US and if a teacher chooses to use it, it is as a help to the student. In Canada it is to own you and show how stupid you are in comparison to the teacher.
2. The US is all about multiple choice. Even for classes you wouldn't expect. And if you know how to take a M.C. test that could be an advantage.
Remember this is only one persons experiance at one Canadian and one US school