Developmental baseball. No focus on scores, outs, and runs. Basic skill building and enjoyment of the game. "Reduce impact" baseballs are used to reduce chance of injury. Each two-hour session is usually 30-40 minutes of practice with the rest of the time devoted to games where the score is not tracked. 45 foot bases.

Competitive baseball, but coach-pitch. Up to seven pitches to put the ball in play, and players can strike out. Typically, the ball is put in play every 2-4 pitches, so fielders don't get bored and get a LOT of chances. Young batters benefit from getting good pitches to hit every at bat. The game moves quickly, which is ideal for players in this age group. 60 foot bases.

Regular, kid-pitch little league. A few small tweaks for this age group (e.g., 4 outfielders). 44 foot mound with 60 foot bases.

Major league style baseball (aka "Bronco" rules), including leadoffs and balks.  Only three outfielders and no restrictions on stealing bases.  Fifty foot mound with 70 foot bases.