I grew up in western Penn, it was called pop, a few hundred miles to the east it was called soda, in the southeast it was called soda. After I started my traveling days I began calling it 'soda-pop' just for the hay of it. And then there are the places where it is all coke, it doesn't matter if it is really root beer or what, they'll call all pop coke. So if you'd ask for a coke they'd ask 'what kind.' At the same time in a large percentage of areas a soda meant an ice cream type drink, like a milk shake or a root beer float, as in a 'soda joint' or 'soda fountain' which is the type of establishment I think Marilan Monroe was discovered in.
Another is dinner versus supper, my mother made supper, alot of others made dinner, even though it could be the same food and same time. There is a technical difference if you look the words up, but in this sense it doesn't matter because you're talking about how people talk, which often has nothing to do with being technically correct.
To my knowledge 'restroom' only came into play in places of business, everywhere else people went to the bathroom, or as I've almost always referenced it, "to the library." I read many a Readers Digest in there during my growing up years, today, the book selections have changed but there is still reading material.
In the late sixties when I began traveling around the country these type of differences were more dramatic because fewer people had traveled as far and as much as is common today.
One I have never been able to track down and figure out is 'red up,' my mother would say 'I have to red up the house before so and so gets here,' meaning she was going to pick up, straighten up, clean, the house. I haven't a clue where that came from or how it came about.
There used to be countless different references for the same things in this country and I used to have quite a bit of fun with it in those ealy days, with a lot of them you could tell a person where they were from just in what they would call something.