Refer to the site
https://flightaware.com/live/cancelled/yesterday/CYYZ for flight cancellation data. For yesterday, Air Canada cancelled 6% flights out of Toronto, 3% out of Vancouver and 6% out of Montreal. Westjet on the other hand cancelled 20-30% of its flights. In last many days this number has been in 4-6% range. Most of these cancellations are on multiflight routes, improving profitability of Air Canada.
Even if you assume that Air Canada has more aircraft equipped with additional equipment for better landing in bad weather, both airlines will be impacted by weather in more or less same way. Not sure, if Westjet is cancelling for crews or not but why are Air Canada cancellations so much lesser than US arilines?
For any airline, pilots (and FAs) are most critical roles to run operations. Large airlines need labor (crew) operating flexibility to be able to respond to unpredictable changes. This is always a point of discussion in union negotiations of any airlines. During COVID, Air Canada struck a deal with its pilots and agreed to keep more than required pilots (to enhance flexibility) but at lower operating hours on an average.
In AC, a pilot is promised a min and max. # of hours a month/year. If you have more than required pilots, you can manage the cost by allocating min # of hours. If there is sudden increase in demand (or sickness), there will be enough pilots to run operation smoothly. Since, US airlines are running closer to 2019 capacity (and lesser pilots), they don’t have enough buffer.
AC on other hand is running @ ~50% capacity of 2019 with higher available pilots (with lower number of monthly hours). AC has buffer without increasing the pilot unproductive cost. This is how good relationships with unions help organizations. As demand/capacity increases, pilots will continue to get back to normal hours.
Same logic applies for FAs.