Lol. Clearly you haven't spent much time in either city because that's about as far off the mark as is possible.
Detroit is America's "Shrinking City". People, especially the white people who had the most money, abandoned it. Over 80% of the population is black in 2012 and the crime rate is one of the highest in all of the gun-crime country, United States. Population, economy, everything is going down there. For example, GM got rid of huge deal of factories there and moved them out of the city to somewhere else. Environmentally, that's all good for Toronto cuz less pollution generated from smaller Detroit and its area will flow into GTA on the Westerlies.
Montreal is Canada's abandoned city. The French took over(?) it in the 1970s to avenge all who spoke English language, and the stupidity of discrimination against English speakers went on for decades and Quebec, where Montreal belongs, still is an officially French Only province. Great deal of money and people moved out of once the largest city in Canada including most of the major banking institutions' headquarters. As the province elected Parti Quebecois, a separatist provincial party again in 2012, the trend continues. (But they won't achieve the party's ultimate goal of separation from Canada since 1970s, which will then lead them into utter destruction into nothingness either through an economic war or a physical civil war.) By the way, Canadian central government isn't like most others in the world including France (on Bretons), China (on Tibet and Uyghur), US (on most territories they conquered) and Japan(on Okinawa). It allowed the peace and freedom (even if it meant against the majority of the country's will, stability, and unity) so long as there is a democratic agreement in the "province". Quebecers should thank Canada for the generosity if any, and should not pursue one step further which will make even the angelic(?) Canada mad and put everything upside down.
Well, another interesting fact is that something like 80% of Asian immigrants and 50% black(mostly and strategically brought from Francophone countries) immigrants move out of the city and the province in about 5~10 years. They are not as foolish as Parti Quebecois might want them to be, nor hateful against rather a great country (as a whole) called Canada whether francophone or anglophone. Only the poor victim of Montreal is stagnating, if not shrinking economically. What we see in Montreal, still beautifully planned and monumental, only shows how great and mighty the city Montreal once was for so long until about 40 years ago. One can only imagine what it would have become, if Montreal became/ continued to be officially bilingual, equal to both French and English of the island and the greater area in the rich lowland prairie, instead of bashing the damn English bastards(an expression used by Rene Levesque, Founder of Parti Quebecois) in 1970s. It might have been a match for New York by now.