When you put your money into a structured pension plan for your retirement then it's tax avoidance since you are avoiding paying the tax you normally would if you invested it in some other way. Tax evasion is where you break the law by hiding money that should be taxed. Quite a big difference.

Haven't read much about this, but the two potential scenarios (for businesses or individuals) are:

1) Legal: Take advantage of different national/state tax laws, exemptions, etc. and conduct business within those territories or have money move through them in a way that you minimize your tax obligation.

2) Illegal: Just lie about what money you have. Hiding it in offshore accounts and funneling it through intermediary channels when you want to make use of it.

You don't see a difference in whether or not you're breaking the law? Even if you believe that the law is disconnected from morality (not totally true, but more true than I would like), breaking the law still means that people with guns can put you in prison.

There's a real fundamental difference between having people look down at you as a conniving scoundrel who took advantage of the law, and being behind bars.