Huge difference to be honest. Canadian ones (same as in US I think) were more like belletristic texts written with the goal to give basics without too much thought needed by the reader.
In contrast you cannot approach Soviet text math book without serious thinking effort. You need to overcome some mental barrier to get into. If you cannot do that then this is not yours - choose something else.
I believe that is because of different motivations of high-school systems. University on the West gets its money directly from students so they motivated to attract and keep as many students as possible - so books are entry level to do not scare students. Barrier here is established from "paying user" side.
In USSR universities were getting money from state/society as education was free so they must maintain those barriers so only those who went through were there. Barrier here is from "service provider" side.