Different breeders may use the terms slightly differently from each other, so ask the breeder if you are not sure.
In my lines, an okeetee is a normal corn that is, to the best of my knowledge, (although I did not catch the ancestors myself, so can't guarantee lineage) descended from animals from the okeetee area (Jasper County) in S. C. I (just like many other breeders) have been breeding them for many generations to try to produce animals with the bright colors, thick borders, thick black belly checkers, lack of dark longitudinal striping (common on wild caught okeetees) that has come to symbolize okeetees these days. Try to find a wild one like that - you will probably look a long, long time, lol! Although the wild corns from that area are often pretty, and often show some prized okeetee traits, very few will look anywhere near as pretty as a typical c.b. baby from a long line of selectively breed okeetees. But not every c.b. baby from outstanding parents will look as good as mom and dad do...and of course, some will look better. But most will probably look similar to their parents and grandparents. It can be difficult to tell which are the best babies, until they are several months to a year old. Looking at the parents may be more helpful than looking at the babies themselves.
In my lines, "classic" corns are any normals that I think will be prettier than usual, but they are not specifically okeetees or Miami phase. They could have some of those lines in them, or some bloodred, or just a mixture that has produced what looks like will be a really pretty normal corn.
Many other breeders will use the terms the same way I do. But when in doubt, ask.