I bought one of those rod tools before I fully understood the process. Now I'm not sure if the steel rod I bought is meant for honing or for sharpening. Is there a way to tell the difference simply by the look/feel of the steel?
If it's a rod, it's for honing, not sharpening. As stated in this article from Serious Eats:
One of the biggest misconceptions about the particular type of kitchen tool you see above is the belief that it's a knife sharpener. It doesn't help that many manufacturers sell their honing steels as such. But a honing steel is not a sharpener. Ridged, rod-like honing steels, or "stropping irons," as they're sometimes called, do not sharpen blades; they realign them.
If its a sharpening steel it should be abrasive, and if its a honing steel it shouldn't be. So, in theory, you should be able to rub it across some metal about as hard as knife steel and mar the surface or leave scratches if its an abrasive sharpening steel, and a non-abrasive honing steel wouldn't mar the surface.
When a knife's edge becomes dull, you can reset the edge with a diamond steel or ceramic steel. The difference between a diamond steel or ceramic steel and honing steel, is that a diamond steel and ceramic steel will actually grind away material from the knife, allowing it to reset the edge.
I don't know how to tell if it is a diamond steel on inspection.
A honing steel is often called a sharpening steel.