Could you please tell me if Concordia and UBC (Canadian B-schools) are better than George Washington and Tulane Freeman (US B schools)?
You ask a very common question, "Is school X better than school Y?", that has no simple answer.
Business schools are very different than other professional programs. If you had asked "is law school A better than law school B?" or "is med school #1 better than med school #2?", you'd get a fairly straightforward answer. However, business schools are a lot more complex.
The first thing to note is that every business school has a unique program and, even more importantly, network. Since networking is one of the primary benefits of attending business school, you need to identify your target network before choosing the program that best suits your needs.
So, for example, if you want to work in Vancouver (or even the Pacific Rim in general), then Sauder (UBC) is going to give you great contacts for your post-MBA employment. Tulane, on the other hand, is on the opposite side of North America and, even though it's a respected school, would offer little or no employment opportunities on the West Coast.
Second, you need to think about what skill set you hope to gain, since different schools offer different specialties.
Third, you need to think about your own learning style and what programs teach the way you like to learn.
It's certainly possible to do a google search on those schools and see where they lie in various rankings, but there are a lot of different rankings out there and not all schools choose to participate (not many people know this, but it's actually very expensive for schools to participate in rankings and some choose to spend their money elsewhere to recruit in different ways). Rankings can be a useful guideline, but finding the school that's going to get you gainfully employed in your field of choice is far more important than where the school sits on someone's list.
Good luck in your studies!