How are they different?
I fell in love with a Canadian university which is really good in engineering and is surrounded by an incredibly supportive tech culture.
I really want to get in, and if I do, I’ll most likely attend.
However, I don’t really understand college admissions in Canada, so any advice would be much appreciated. Thanks 
Waterloo ?
To the best of my knowledge, as an international student in Canada, you will be required to pay the highest tuition rate = International Student rate.
Basically the same as in the US but with a heavier if not exclusive focus on stats: UW GPA and SAT/ACT scores. Financial aid for internationals is very limited.
We applied to multiple universities in the US and to multiple universities in Canada. One daughter went to a university in the US, the other went to a university in Canada.
Many of the Canadian universities do not require essays. This makes the application simpler. Also, admissions in Canada is relatively predictable and largely based on grades, with the larger schools using SAT or ACT scores as a cutoff. In contrast admission to our in-state flagship was similarly straightforward and predictable, but other schools in the US tended to have longer applications and less predictable admission (particularly the more selective ones).
Also, financial aid for international students is very limited, but costs are lower and are paid in Canadian dollars (which has been weak for a few years now). This makes it easier to predict up front what it will cost. We did get some merit based financial aid from the less well known and smaller schools that both daughters applied to, but we were not offered any aid from McGill (this was true for me also many years ago, but back then McGill was very inexpensive). However, all of the Canadian schools that we applied to were affordable for us with no aid, so we didn’t worry about it at all. We did not apply anywhere in Ontario and therefore did not use the Ontario equivalent of the common app.
Good luck with your admissions. If you have the grades, your chances are excellent. If you don’t have the grades for the top schools, your chances would be bad.
Canadian engineering admissions is a little different from the stats based admission for most other Canadian programs. At both U of T and Waterloo, there is a video interview which counts for a fair bit. Waterloo also takes extracurriculars into consideration. If the university is Waterloo, you should search the net for Bill Anderson Waterloo admissions blog. I can’t provide a link because it’s a blog and CC won’t allow it. Bill Anderson is the admissions director for Waterloo admissions. He specifically addresses admissions for international students in his chances for 2018 post.
If your university is in Ontario, you would apply using the OUAC 105 application. That would be your first step. The engineering programs you apply for would then send you their supplementary application instructions.
It’s in your best interest to submit your application as soon as possible, no matter what deadline the program has.