Fox,
Normally, and I stress Normally, the short block is the block with the bottom end in it. A long block is the heads, cam and intake with the block and bottom end. Some crate engines are ready to run and others have to have pulley's carbs, and other wiring added. It seems to vary from one manafacturer to another. If you have good heads, intake, cam and etc. then the short blcok can save you some money. Before ordering I would contact whomever I was going to order from and ask them just exactly what all is included in their particular short block or long block assembly. Most engines you have to supply the carb and I think on all the headers unless you order them seperatley with the engine.
Ron