What is the difference between a prehung door and a slab door?

A prehung door is a complete door unit that includes the door slab, frame, hinges, and a pre-installed jamb. It is ready to be installed into a rough opening. The prehung door is convenient because it eliminates the need for measuring and cutting the door to fit the frame, making installation easier and quicker. On the other hand, a slab door refers to just the door slab itself, without the frame or hardware. Slab doors are typically used to replace existing doors while keeping the existing frame intact. The advantage of a slab door is its flexibility, as you can choose your own frame and hardware. However, it requires more effort for installation as it needs to be aligned and properly attached to the frame.