There may be minor differences such as number and size of prep bowls offered in the package, but the main difference that I see is that the QB1004 has a 450 watt motor, and the QB900 has 400 watts. Also the blades used in the 48 oz container differ - the QB1004 has 6 blades, and they are at an angle. The QB900B has 4 blades and they appear to be horizontal.