Ask for pop at the C-Store and they'll point you towards the Mountain Dew. Ask for a pop in Maine and they may punch you in the teeth.
It's rare that anyone really speaks the same language. Regional dialects result in different words and phrases for the exact same thing. One study focuses entirely on soft drinks. By a landslide, the North prefers "pop," the East Coast drinks "soda," and much to the chagrin of Pepsi, those down south enjoy a nice "coke."

