I'm not as familiar with GR2004 even though I own the game. From what I saw of it, I didn't like it much and quit playing it. It appeared to be focused more on the jockey rather than the horse. I'm not interested in riding other people's horses. I want to build my own horses up and breed them to produce even better horses. That's exactly what GR2006 does. GR2006 appears to be more focused on building stats, winning titles for each horse, and then breeding them to run in LOC events. I even like the idea that you can share horses with other players to breed into your lines. Hope this helps.