Millions, I think a lot of synthetics use Aluminum Oxide as the main abrasive agent.
Stones and rods do different things. With usage over time, the metal that composes of the edge and immediately behind it gets fatigued and can slightly bend/microchip off. Sharpen using stones to re-establish or touch up an existing bevel and remove the fatigued steel, revealing fresh metal at the edge.
Hones can somewhat re-align a fatiguing or slightly rolled edge but keep in mind this isn't a total maintenance type solution. It's still unclear to me what they do for steels that tend to chip and abrade more easily than bend.
Hones can also add in some scuff/teeth to your edge to keep it going between sharpenings. Depending on your usage and preferences you may or may not like the slightly toothy feel.