A suspension lift raises the vehicle's frame (chassis) away from the axles by replacing the springs with taller (or more arched) springs. A body lift raises the vehicle by lifting the body away from the frame with spacers. This keeps the frame at its existing distance from the ground. A suspension lift is recommended for anyone planning to use their vehicle off-road while a body lift is recommended for anyone that wants to make their vehicle look lifted with no true intentions of going off-road. This doesn't mean that a body lifted vehicle can't go off-road. It just won't perform as well as a suspension lifted vehicle because it hasn't gained any ground clearance. Suspension lifts for the Jeep Wrangler YJ typically range between 2-inches to 4-inches (though there are some companies that produce "extreme" kits in excess of this), while body lifts range between 1-inch to 3-inches.
A suspension lift is more complicated than a body lift because it alters all of the suspension components that give the vehicle its factory ride characteristics. Taller leaf springs are typically stiffer than factory leaf springs so the vehicle will have a harsher ride quality than with soft factory springs. Longer shock absorbers will be needed. The vehicle will also have a higher center of gravity because the entire weight of the vehicle (everything except the axles) will now be raised further from the ground. In some cases, the transfer case will need to be lowered and the rear differential repositioned to minimize driveline vibrations as the Jeep Wrangler is notorious for having a short rear driveline that isn't readily accepting to increased u-joint angles.
