The quick change handpieces have a spring loaded or rotating lever that allows burr changes without needing to manipulate the chuck or find a chuck key. Users such as jewelers that might need to change between many different burrs repeatedly like these. But they are limited to 3/32 shaft burrs only. For relatively light duty. precise, tiny work. Your handpiece is not a quick change model.
The 30 and 44 handpieces are much more heavy duty, and are not interchangeable with the full line of Foredom equipment. They require a different model motor and flexible shaft than the one you have. These are probably more appropriate for engine type work, carving, etc, things that need more time, pressure and torque without bogging down. This is where people decide between these electric tools vs. small or mini air die grinders. Also, the 30 has a traditional style 3 jaw chuck, a small Jacobs actually, size 0, but only accepts up to 5/32 burr shaft. The 40 takes collets, up to 1/4 available for the bigger burrs.
However, the handpeice you have is still a great tool, and a nice
step above Dremel. Once you use it, a Dremel seems like a toy, in my opinion. Start out with it, see how you like the feel of it. It gets better as you move up through their product line. But after you have used it, you're in a better position to decide what kind of upgraded hand piece might be even better for your particular needs.
