How to Replace an Exterior Door

What is the difference between a door jamb and door frame?

It is common for these terms to be used interchangeably; however, a door jamb refers to a specific section of a door frame. A door frame is composed of two side jambs on either side of the door and a horizontal head jamb across the top of the door.

Can you just replace a door without replacing the frame?

Yes, given that the door frame is in good condition and the slab door is a compatible size.