Brianna said:
but the UK needs only 4 years to complete bachelor's and master's, as opposed to 5 years in Canada.
Typically in Canada it's six years... four years for a BSc plus two more for an MSc.
Something to consider though, is that it's rare for someone to do all of their degrees at the same institution (at least in the Canadian system). And really, you have to look more at the details, particularly for graduate school... what subfield you want to get into, the specifics of your project, who your supervisor will be, etc. For Canadian universities, when it comes to undergraduate education, the differences between schools tends not to be as wide as it can be in other places (though I can't speak specifically to the UK system). Canadian undergraduate physics programs tend to be reasonably uniform in my experience, and so that allows you to factor in other parameters into your decision... cost of living, geography, tuition, facilities available to students, co-op programs.
caz said:
cannot speak to the universities, but there are few reasons to get a master’s before applying to Ph.D. programs. This is a US perspective.
In Canada it's rare for students to go straight from a BSc to a PhD program. It's a lot more common to enroll in an MSc first. That said, the MSc typically comes with financial support and students can either transfer into the PhD after their first year or so of the MSc or complete the MSc and then enroll in a PhD program, with the MSc coursework counting toward that of the PhD.
One of the main advantages of this approach is that it allows the student to enroll in graduate studies without committing to a 4+ year project. If it turns out you don't like the particular sub-field, or project or supervisor as much as you thought you might, you can complete the MSc and move on.