Oh, I thought I'd do a "if you don't know what all that stuff means then you don't need a 1Dx".........(grins).
It's just that the 1Dx offers more options as expected, and that's just one of them. The numbers are not the same on either camera, i.e. level 10 on 1Dx does not equate to level 10 on the 5D3. The # levels are simply "quality" levels, and are not necessarily standardized to anything.