name preferences: general vs specific, causation vs correlation
I suspect that there is a correlation between areas of the US where carbonated beverages are called soda vs pop and areas where Coke is preferred over Pepsi. Is this correct? If so, what might cause it? Beverage companies using their preferred general term as they expand out from their HQ?
And can this be generalized to other examples of specific names vs general names? For example, does the use of lightning bug vs firefly correlate with terms used for insects, or for interesting things (cool, rad, ...)?