Yes, there is a difference. Tax evasion, we all know, is unlawful and unethical, and it's very harmful to our economy. Tax “avoidance” is effectively a term used to define tax planning. As Canadian taxpayers, we all have the right to organize our tax affairs in such a manner as to pay the least amount of tax that we are legally obligated to pay through law. That is the fundamental difference.
I think where it gets confusing, though, is in the area of aggressive tax avoidance. Already, others here have mentioned that aggressive tax avoidance is really where you get into not planning your tax affairs in the spirit and the intent of the legislation of the tax policy.