
Rory calls carbonated soft drink “soda” while Dean calls it “pop”. Both words are correct in the US, with some regional differences. Pop is more commonly used in the Midwest, while soda is the more common word in New England.
Footnotes to the TV series

Rory calls carbonated soft drink “soda” while Dean calls it “pop”. Both words are correct in the US, with some regional differences. Pop is more commonly used in the Midwest, while soda is the more common word in New England.