Belt drive uses a small spinning wheel with a rubber band wrapped around part of it. The other end of the band is wrapped around part of the platter. It’s like the mechanism in the car where the small “wheel” sticking out of the engine has a belt going to the main fan to make it spin.
A direct drive turntable has a motor right on the platter. Many now use the design of when you turn on the turntable, a magnet pulls the platter in place and the motor spins…hence why you should not remove the platter while the TT is on.
Vineoak said it best. When I started on belt drives, I would have to condition myself to put enough strength (but not too much) when I released the record so it would spin at the right speed. Or else you hear it go quickly from slow to normal.
With direct drive, the motor is more powerful and thus you don’t face this problem as easily.
I don’t think any DJ turntables now are belt drive anyway. Do you want to get into vinyl? Or use midi control?