I do believe that ends this thread.
Anyway, it has to do with area, age, and influence.
Mom calls it pop cause she was raised up north, I used to call it pop, no one knew what it was cause I was in Florida, so I said soda-pop for a long time when I was a kid. Now I call it soda. Pop feels old, calling all soda a coke feels old, soda feels like the norm. But, to each their own. There's no 'right' or 'wrong' thing to call it, unless you're calling a soda a floogimishkintal...in which case, yes, you're wrong, and you're weird.