Mexico remains New Spain, with the support of a European colonial empire, more cohesive. Canada somehow goes its own way (the Canadiens establish independence alongside the Thirteen Colonies and
Quebec-Canada is an independent but backwards and cold republic with heavy feudal baggage?) and experiences a lot of difficulty, ripe for Yankee picking.
Hmmm. Does Q-C take Rupert's Land? You could have the corollary of the Mex-Am War with USA fighting Q-C in a land grab, and end up with the Canadian West instead of the Mexican north.
Or, USA might end up with RL in War of 1812 (if it still happens) if Britain has held on to RL.
Britain may develop British Columbia if it doesn't have a land access from the east. If that becomes the plan, Britain will squeeze the USA and Spain out of the Oregon/Washington region. Edit: or Britain doesn't make a fuss if it doesn't have Rupert's Land and USA ends up with British Columbia.
Or Britain sells RL/BC to USA.
There's a whole lot of butterflies that need to be sorted out before you can simply swap Canadian and Mexican fates. PODs that allow socio-economic revision also change geographic borders. A stable Mexico prior to Mex-AM War butterflies that war. A turbulent Canada has to happen after they acquire Rupert's Land, or Britain won't hand it over.
So, IF we want same borders, the POD has to happen late 1800s. That's hard to see for Canada especially.