It's probably a little shallower, but wider. I think the 1 micron diamond edge is a good bit more refined and the preference for the yellowcake is due to speed and being "good enough".
yellowcake on the buffer is somewhere between finest oilstone and 1 micron diamond on wood.
The other thing that I sometimes find with a diamond edge on cast is little defects in the edge after stropping (the kinds of defects that PPA would not care about at all). I didn't find that occurring on wood, but wood also takes longer and consumes more diamonds. 1 micron diamond on wood is completely invisible to the microscope, both on the back and at the edge.
I'm not convinced that one is best for chisels and not another is better for plane irons, though - but yellowcake is great for planing anything less than perfect. In perfect wood, I think buffer on bevel down planes is a lateral move unless we get really specific (like down to the washita/linde-A edge, and then it's not a superiority in terms of potential, it's the no-contamination, fast finish that's better than doing all of that by hand).