I concur with Keith's comments above about people being pretty much the same in both countries.
I have, however, noticed that there are small but significant differences in the behaviour of customs officials in the two countries:
The American customs and immigration officials can sometimes be quite belligerent - it's almost as if they have this "I've got a gun, and that makes me all-powerful, and my job is to protect my fellow citizens against aliens like you."
The Canadian customs and immigration officials, on the other hand, tend to be a lot less high and mighty, but can sometimes be a little bit dumb. I recall importing my (Canadian purchased, Canadian registered, Canadian plated) moto back into Canada by air once, and having enormous difficulty convincing the customs person that it was "Canadian goods returning", and therefore no different than a Canadian vehicle returning into Canada at a land border crossing.
After finally overcoming that conceptual hurdle, the same customs official stated that the Agricultural inspection folks would need to inspect it for possible presence of bugs or other insects on any dirt that might be on the tires. I told the woman that there was no dirt on the bike - I had very carefully cleaned it before shipping it - and she told me that she was not qualified to assess agricultural hazards. I then had a heck of a time convincing her that I was not asking her to assess the presence of agricultural hazards, I was only asking her to assess the presence or absence of dirt on the bike - something she finally agreed that she might, just perhaps, have the skill and competence to do...
So, I guess the bottom line is that it's a bit of a crap-shoot no matter which country you go to, the only thing that differs is the rationale behind the potential headaches that the customs officials might create for you.
Be sure that you are in a very calm and relaxed frame of mind when you go to clear the bike out of customs, no matter which country you go to.