l have a friend who told me that the ski trail rating system for Canada is usually one grade lower than USA is rating system.For example:

Canada is Green = USA is Blue
Canada is Blue = USA is Black

Which means if you can ski blues in Canada you can tackle the black runs in USA, although you may not be able to in Canada.l find this kind of hard to believe, can someone verify if this is true?
Since, l live in California can someone give me a general comparison with the ski trails up in Canada?

Ski Areas in North America use the same symbols. Green Dots (Easiest), Blue Squares (More Difficult), Black Diamond (Most Difficult), & Yellow Ovals (Freestyle Area).

A Canadian Green does not equal an American Blue, An American Green, or even another Canadian Green.

Trails r rated according the trails only at that specific mountain & how the trail is rated is solely up to the mountain management. A Double Black Diamond at Tremblant may have a less steeper grade than a Single Black Diamond at Whistler. Both r in Canada.