Ok so. A baseball is like a basketball, but smaller. It's white instead of orange, which is pretty boring, personally I prefer the basketball. You sling it really fucking hard at a guy wearing a mitt instead of throwing it into a hoop. An eyeball is the organ in my fucking skull that has the misfortune of watching me log in on this hellsite. And a tennis ball is a little green ball you slam with a net, to try and hit over another net. Lots of nets and greens involved in tennis. Terrible sport, don't recommend.