I grew up in Canada, but most of my adult life has been spent in the US. I'm more American than Canadian, but I keep in touch with the old country.
Moving back and forth between Minneapolis-St Paul (MSP) and Montreal (YUL) so many things are similar that the differences can come as a surprise. Some of the smaller differences are most interesting.
Of course there are the differences we all know about, such as the two Ms: "Medicare"  and the Metric system. Both came in during my childhood. For a poor kid in Quebec in Medicare was a flaming miracle. These two are obvious and large differences , but I doubt either would pass in today's Canada. I wonder if Canada and the US were more different forty years ago.
Montreal is poorer overall, but only relatively - it's obviously a wealthy region. Although inequality seems to be growing, it's still far less skewed than the land of the GOP. Education in particular is much less of a local responsibility. Public schools and buildings are spartan everywhere in Montreal, but luxurious in MSP's wealthier suburbs. Overall Montreal's non-historic structures are more minimalistic, more built to budget than similar places in MSP. Concentrations of poverty are also less severe than in MSP .
Montreal's automotive infrastructure is abysmal. Despite the astounding collapse of a major bridge , MSP's roadways are much better. There's now a desperate traffic paralyzing catch-up roadway rebuilding in Montreal so it's fortunate that Montreal has a vastly better public transit system than MSP. On the other hand MSP is now extending its light rail transit system. The two are converging.
Other smaller similarities and differences are perhaps more interesting.  Both Montreal and MSP have very extensive bicycle trail systems that have expanded over the past ten years. In last year's rankings Montreal was rated #1 in North American and Minneapolis was #2 (take that Portland!). That's despite climates that are wintery (MSP) and miserable (Montreal) .
Accessibility is a very big difference. MSP is largely accessible; most of the city can be navigated in a wheelchair and most of the restaurants and private businesses are accessible. That's not a local virtue, it's a legacy of the astounding American Disabilities Act of 1990. Montreal is almost completely inaccessible. It's an vast gap to MSP's advantage, and seems little remarked on in Montreal. You don't want to have physical disability in Montreal.
It's not just physical disabilities that are a problem in Montreal. I have a good understanding of the 'special needs' experience in MSP and some knowledge of how Montreal performs. I guesstimate MSP is about twenty to thirty years ahead of Montreal in its care of cognitive disability in school age children. I see convergence here too however. Montreal seems to be improving, and Minnesota is regressing. Still, like physical disabilities, MSP is curiously ahead of Montreal in the management of cognitive disabilities.
Both cities have good and bad restaurants, but only Montreal has pastries. Sure, MSP has places that sell excellent bread (including baguettes) but you can't buy a pastry in MSP.
Ok, I admit, there are places in MSP that claim to sell "pastries", but the best of them are weak sugary things that would disgrace a Montreal strip mall. The Bagel-gap isn't quite as wide, but it's still there. These are puzzling market failures.
The case of the Aero bar is even stranger. My daughter loves these mundane chocolate bars, but they are sold only in Canada. There has never been a serious modern attempt to sell them into the US market. Strange.
There's one last curious distinction that is personally annoying. In MSP most cafes and libraries have open public WiFi access. Even many McDonald's have it. The entire city of Minneapolis has a WiFi network (though it's not free). In Montreal I have a hard time finding any access at all; even Starbucks charges for access here. I suspected liability or regulatory differences, but that doesn't seem to explain the difference. I wonder now if it's because of the monopolistic Canadian telecom industry, and if open WiFi will disappear in the US as our market consolidates.
Will these gaps close over the next 30 years? I suspect so. The US will, very slowly, go metric in many ways, though perhaps not in temperature. Aero bars will surely come to MSP before I die, though pastries may take longer. The Bagel gap will close, already MSP does well with bread. The US and Canadian health care systems will probably converge on some messy compromise. Open WiFi will disappear everywhere. Montreal will have to do something about accessibility as its population ages. Both cities will become more cosmopolitan, less pale, more multilingual.
The worlds will continue to converge.
 How'd the US system for care of the elderly get the same name as Canada's universal coverage? Some time I'll have to research the etymology.
 After all the investigations it looks like the primary cause was a manufacturing error.
 By US standards MSP is relatively enlightened, which means by Nordic standards MSP is the first circle of Hell.
 Languages differ of course. Montreal is predominantly French with a lot of English (still), MSP is predominantly English with a growing Spanish segment. Both cities look very pale to me, but MSP is a shade less melanin-deficient. Montreal is historically Catholic and now largely indifferent, St. Paul is historically Catholic (and French) and still somewhat religious. Minneapolis is historically Lutheran, now indifferent. Both are river cities, Montreal has the St. Lawrence, MSP the Mississippi. Both were French/English meeting places.
 Montreal has the worst climate of any city outside of maybe Moscow. It's not the cold, it's the frequent freeze/thaw cycles, the endless cloud, the slush ... Yech. Growing up in Montreal is why I think MSP's climate is wonderful, which appalls my native colleagues.
 Open WiFi nets are a favorite haunt of traders in illegal pornography.