I bumped into this article and found it quite interesting: The dude map: How Americans refer to their bros ? Quartz
The main thing to take away here is that even though people in a country speak the same language, they may have a preference for which words to use. I guess that probably doesn't come as a surprise to anyone, but it's still nice to see a bit of research on it.
Further, it's a good argument for avoiding writing "in dialect" to show that someone's from a different part of the world/country. Instead, pick some word that your local characters don't use at all, and have the "outsider" use that word a lot.
The main thing to take away here is that even though people in a country speak the same language, they may have a preference for which words to use. I guess that probably doesn't come as a surprise to anyone, but it's still nice to see a bit of research on it.
Further, it's a good argument for avoiding writing "in dialect" to show that someone's from a different part of the world/country. Instead, pick some word that your local characters don't use at all, and have the "outsider" use that word a lot.