Muledeer: I have owned and successfully Hunted with both "calibers/cartridges" in question here.
I specifically remember the reason the fine folks at Big Green "changed" the caliber designation of the 7mm Remington Express back to 280 Remington - and that reason being folks (both buyers/users and sellers) got the 7mm Remington Express "cornfused" with the 7mm Remington Magnum!
The 280 Remington (7mm Remington Express) is one of the finest of Remingtons proprietary cartridges and no matter what it is called this cartridge works wonders on game up to and including Elk, IME!
Hold into the wind
VarmintGuy