I cannot imagine it is simply one thing, but here is what I am noticing that seems to be what is discernibly different.
1) Mobility - I still get the impression this is greatly reduced in Canada compared to the US. Not because of inter-provincial restrictions really. But because of US border closures. A far big portion of the Canadian population travel Internationally (to the US) than the US population leaves the US. The majority of our worse provincial outbreaks were actually traced back to the US.
2) Gradual reopening (but not really a 'lock down') - A lot of provinces actually never really locked down or had stay in shelter orders in the first place. But there was a far more methodical proceeding through the Phases based on metrics similar to those suggested by CDC and others.
3) Contact Tracing - By virtue of reopening with a lesser case burden, testing still remains fairly accessible. Turnaround time remains under 24 hours (making it actually useful). Some provinces like BC take your name and number at any dining location for example, even on the patio. Thereby actually making contact tracing feasible. There is a small army of contact tracers in each province. The blue-tooth handshake app from the government has pretty quick uptake.
I hate to send the wrong message, because I think the worse the outbreak is, the more measures need to be put in place. But there is a misperception that Canadians are locked in shelter and living in bubbles. It's quite literally un-discernable where I am right now from normal. I think it is more "normal" here than the US. Other than I think most Canadians have diverted their pleasure activities to socially distanced outdoors. Provincial parks are slammed (but there is the benefit of A LOT of space). The malls were open in May, movie theatres were open in June. There is not even mandatory masks in the hospital I am in... Yes, really. It does kind of give me the heebie jeebies.
I honest to goodness have never actually seen COVID or know anyone who has it.
I think this was achievable because of all the leg work that was done early on. I felt like all the time the lock-downs the US bought themselves were subsequently squandered by impatience.