Both, and more importantly the result you are trying to achieve.

For example .50 Chromium Oxide, Diamond and CBN will all produce very different results of all the same grit size, mostly because of the grit shape. Additionally the stropping medium will also affect performance.

Diamond will cut deep and on a razor can make the edge harsh, on a knife or tool that may be a good thing. Chrome Oxide will smooth a Diamond edge and make it more comfortable. CBN can do both, depending on the substrate.

For razors, pasting is done mostly to create smoothness, most begin with Chromium Oxide, but Razor Quality Chrome Oxide is different from buffing “Green” polishing compounds, which often contain little or no Chrome Oxide.