Lift kits vs system?

Hey R/4x4, I have that black 94' f-150 I posted a few pictures of, and I'm thinking I want to lift her maybe 4-6 inches. Can you give me some advice on weather I need a lift kit or a lift system?

Edit: Since a lot of you are asking, www.autoanything.com sells two different kinds of lifts. A lift kit, and a lift system. The kit has almost no information, but the system lists nitro shocks as well as a whole ton of other things found in a suspension lift. I figure that their "kit" is a body (block and torsion key) lift and the system is a suspension lift.