What makes indoor racing different from outdoor racing other than the obvious is that indoor race tracks are typically around one minute in length and outdoor race tracks are typically two minutes in length. Indoor racing tracks have consistent jumps, obstacles and grooming while outdoor racing tracks have much higher speeds and the tracks get rougher and more difficult as the race goes on.  Also, In Supercross races there is one main race about 20 minutes long.  In Motocross however there are two thirty minute races. 

Dirt bikes themselves are different for the different races as well. The bikes are softened up more for outdoor racing, which means they are made more flexible.  The suspension on the bike is made up softer making it easier on the racer.  In Supercross racing, you want the bikes set up very stiff and precise so it will react immediately to the racers input.  A stiff dirt bike would however be too twitchy and hard to control for outdoor racing tracks.

You can find information on these two types of races on the internet at your favorite dirt bike, or racing sites.  You can find sites on racing gear as well as the races themselves.  If you’re interested in racing you can even find sites with rules and regulations for these races.  Remember there are a lot of different names for these races but typically it is indoor or outdoor racing.