Cyberpower units, though being great UPS units (I have 2 of them), are really confusing in terms of references.
I think it depends on which country you buy them from, since the plugs need to be of that country.
My 2 CP1500EPFCLCD units, for example are rebadged by a company called Nitram in France. BTW, for french people, this is probably the first time I kept the localized instructions of electrical kit, since, for once, they are not garbage french !
End of the day, OP, they are the same units, the "E" is probably for Europe, whatever this means

Just buy the one with the proper plugs, since CP will reimburse your protected kit ONLY if plugged directly (no adapter) to the UPS.