Rich
Sharpening an edge with an abrasive removes metal from the edge. A steel does not, it causes the edge to cold flow. If you look at the edge of a sharp blade with SEM, an abrasive sharpened edge will look like a saw blade, and a steeled edge will be smooth and polished. A properly steeled edge is sharper than an abrasive sharpened edge.
The advantage of steeling an edge is the higher level of sharpness, plus it’s a lot more efficient to maintain a sharp edge than it is to use it until it’s dull, then resharpen with an abrasive. In practice, steeling is more or less analogous to stropping – it’s all about edge maintenance.
I sometimes strop my wood carving gouges, and sometimes I steel them. I think I can tell the difference, but it may just be my imagination. For knife blades, it’s easier to steel them than to strop them, at least for me anyway.