Braces use brackets and wires to apply continuous pressure, gradually moving teeth into the desired position, with periodic adjustments by an orthodontist. Clear aligners, like Invisalign, are custom-made, removable trays that also apply pressure to shift teeth, with new sets used every few weeks. Both methods typically take 18-24 months, depending on the complexity of the case. Braces are more effective for severe misalignment, while aligners are less noticeable and more convenient.