Growing up in Australia, for me a carbonated drink like Pepsi or Fanta or lemonade was always just a "soft drink". (Also, 'lemonade' in Australia was something different to 'lemonade' in the US; it's something close to 7-Up.) So when I moved to Seattle, it was surprising to me that all such things were called "pop". And then I travelling across the US, and realised it was also "soda" (which, to an Australian, is exclusively club soda), and even sometimes "coke". Not capital-C Coke, but "coke", meant any generic soft drink. It's all very confusing.
Thankfully, Ed Chen (a data scientist at Twitter) makes it all clear with this map of the usage of coke, pop and soda around the US:
Ed created this map using the R language. He downloaded geotagged tweets referring to the act of drinking, and plotted the frequency of their use across the US. Very cool. You can read how Ed did it on his blog linked below.
Edwin Chen's Blog: Soda vs. Pop with Twitter