Out here the carbonated things like Coca Cola have always been called "pop," which was a short version of "soda pop," but a "Soda" was just a soda pop with ice cream in it. I've never heard anything about "egg creams.":-)

We had a heck of a time when we first moved to New England. The kids and I asked for pop at the restaurants and they looked at us like we were aliens. We finally remembered to call it "soda." Then my mother-in-law, who was so kind, asked me if I wanted a "tonic water." took me awhile to figure out she meant carbonated mineral water.

kat