well, there are suspension lifts, and body lifts. A body lift increases the distance between the body and the frame using spacers or pucks at the body mounts. In other words, the body is lifted up higer and the chassis stays at its stock height. They are usually cheap (under $100), only go up to 3inches, and are easy to learn how to put in. A suspension lift increases the distance between the axle and the chassis using longer springs (or arched, if leaf springs) they are a bit harder to install. You can get suspension lifts up to 8'' for Broncos. Suspension lifts are generally better for off road...but more expensive.