What are the differences in our cultures? I don't see any as a nation.
I have been all around the USA, and lived all over British Columbia and Alberta, and as a country, the culture is nearly identical. I would feel more at home visiting Washington or Northern California than I would visiting Toronto as an example.
Sure, the US have many different cultures within itself, but so does Canada. A person from the West Coast is going to feel like they are seeing a whole other culture visiting the South, but the basics are all the same.
Same language, mostly same slang, same bus system, same grocery system, same churches, same stores, same tv shows, same road/driving system etc. A person living in America would generally find no major culture shock moving to Canada, and same if it was flipped.
As someone from Toronto, you would obviously feel more at home in New York than you would in Nunavut. The UK would be a foreign land for both of our citizens as well.
The only major differences I see are:
Gun Laws
Health Care System
If you aren't comfortable around guns, there are plenty of states where you would feel at home. Gun laws differ from state to state. In the South, yes, you might see someone shopping in Wal-Mart with their pistol, but there are many states where you are unlikely to ever even see a gun in your life outside of police/military/hunting, just like in Canada.