As in any country, big or small, there are plenty of cultural differences between Mexicans of different areas of the country. My sister was victim of these in a wedding she recently attended in Monterrey.
She was told that it was going to be a garden wedding, whose dress code in Mexico City is purely in light, pastel colours as they are during the day and surrounded by nature. You can imagine their surprise when they arrive at the appointed place and find out that it was not a real garden, but a hall decorated as a garden and the rest of the guests were dressed in night gowns and smokings. All the people from the capital had made the same mistake, so they stood out at the event.
I suppose this shows that you have to check and double-check your assumptions every time, even in your own country.