> The biggest reason Canada is different is that they have a parliamentary system that elects their Prime Minister
Quebec is another big difference–there is nothing really comparable in the US. Spanish is the closest thing the US has to French, but there is no state in which Spanish outranks English–and even if predominantly Spanish-speaking Puerto Rico successfully gains statehood, Puerto Rico would be only a medium-sized state in terms of population, so it will not be able to have the same impact on US national politics that Quebec has on Canadian.
The US has a lot of cultural diversity, but its cultural diversity is spread out thinly, rather than being regionally concentrated – as a result, that cultural diversity can't be reflected in the political sphere in the same way that it is in Canada or the UK or Belgium or Spain, where the distinctive culture of specific regions of the country causes them to develop their own unique party systems.
Quebec is another big difference–there is nothing really comparable in the US. Spanish is the closest thing the US has to French, but there is no state in which Spanish outranks English–and even if predominantly Spanish-speaking Puerto Rico successfully gains statehood, Puerto Rico would be only a medium-sized state in terms of population, so it will not be able to have the same impact on US national politics that Quebec has on Canadian.
The US has a lot of cultural diversity, but its cultural diversity is spread out thinly, rather than being regionally concentrated – as a result, that cultural diversity can't be reflected in the political sphere in the same way that it is in Canada or the UK or Belgium or Spain, where the distinctive culture of specific regions of the country causes them to develop their own unique party systems.