Having spent the last 35 years at a Canadian university, I feel fully qualified to declaim on the subject. First the terminology. Univeristy here covers both colleges and universities in the US. A college tends to be either a technical school or a vocational institution, such as programming or religious, the latter leading to ordination. I will stick to universities.
When I first came here, there was a system in place (actually in the process of being abandoned) in which you could either get an honours degree in a subject or a general degree, with no major at all. There were also “faculty programmes” a kind of very reduced major or, mostly, joint major. One of the faculty programs was in math, physics, chemistry, and biology. Why not call it just general science? The only actual requirements for a general degree were that some upper level courses be included, plus, of course, a certain number of credits. The honours degree, on the other hand, was entirely different. You basically could not do it unless you started it in your first year. Oh, it was theoretically possible, but rather difficult, to go into honours in the second year, but almost no one could do within the usual time. Moreover, from the beginning, the honours students were segregated from the regular students in special honours courses. After a year or so, the general degree was revamped with a required major added. Even so, there were no such thing as distribution requirements. You needed a certain number of credits (90, if you were in a three year program, coming from a CEGEP as described above, 120 in a four year program) and a minimum of 48 in your major subject. The latter is much more than is required by US colleges. IIRC, when I was in college, the major required 32 and honors was just one special course or exam. Getting back to here, the honours degree is even more demanding, requiring 54 credits in the major. A joint honours in math and physics requires 36 in each. In a 90 credit program, this leaves only 18 credits outside the program. I doubt that such a concentration would be permitted at any US school. Inevitably, some of those 54 honours credits are going to be in graduate courses or at least mixed graduate/undergraduate courses.
Graduate school is much closer to the US model. In contrast to what was said above, at least when I was in graduate school, nearly all the students got a master’s before entering the PhD program. And that is true here, although it is certainly possible to get a PhD without the master’s. The main difference is that the master’s here tends to be a mini-PhD with demanding thesis, outside examiners, the whole works. I am astonished that some departments keep students 4 years in the master’s program. They tend to be laboratory sciences and they view their students as cheap technicians.
In general, the best undergrads tend to be better than the best at US universities. But then they go south for graduate school and the dregs remain, so the graduate programs are rather weak. Plus lots of foreign students and the number has gone way up since it has become so hard for them to go to the US.
Although this is based on my experience at one university and provinces other than Quebec do not have CEGEPs, I don’t think the question of concentration and distribution requirements is any different elsewhere. Very strong honours programs and weak graduate schools.