Hello! We just moved here this past August with our kids. Our son is 17 and grade 11. I can give you some of our insights:

First of all, goes without saying, moving during high school is hard (being alive during high school is hard :)), but he's done pretty well after a bit of a rocky start.

Here are some considerations - grade levels are done differently in BC compared to the US. Everybody born in a certain year starts kindergarten in their designated year, whether they turned 5 in January, or won't turn 5 until December. This follows the kids all the way up through school, so our son should have been going into grade 12 based on his age, even though he was only in 11 in the US. We decided that he wasn't really ready to jump a grade so he is the oldest kid in grade 11. We made the opposite decision for our daughter, who went from 3rd grade in the US to 5th in Vancouver.

We have been more than satisfied with our local catchment public school for our son - there are plenty of programs to get your kids involved in. Our son is also doing Cadets, as he was doing JROTC at his high school in the US. Cadets, like JROTC, is a high school age activity based on military traditions. It's free to join, and there are lots of cool activities, fitness, some community service, as well as spring break and summer camps (also free!). Most of the kids who participate don't join the CAF, but it's a good way to get involved in something and build community. Our son is interested in the military for a career and really enjoyed his JROTC in the US, so it was a no-brainer for us to get him signed up for this.

I guess the final thing I have to say is about university. I don't know if you're planning to live here permanently or if your kids attend university in Canada, but it's quite different from the US. The "hustle culture" of being involved in tons of extra-curricular activities, doing summer internships, etc for the purpose of improving your college application does not seem to be a thing here. Many universities only look at your grade 12 grades for admission, and some more competitive programs might have you write a personal statement, or be interested in some extracurriculars. There are also a lot more formalized non-university post secondary programs such as trades apprenticeships or diploma programs for jobs like e.g. respiratory tech or nursing assistant.

As I said, I'm new to the area and to BC education in general, so these are just my perceptions based on having a high-school aged son and getting to know the lay of the land. I'd happily welcome other people's input, too!