They do all serve the same purpose but, they DO NOT all perform the same. The big difference is ridged and adjustable. The rigid bars are stronger and provide the biggest results. The only drawback is that they are harder to install. The adjustable bars are easier to install but provide less performance. I had a ridged bar in the back and changed it out with the adjustable. Let me tell you, i was very disappointed. The rigid bars may cost more but, are well worth the extra saving up time.