It's true that they are different. But PS+ is more than a rental service. You get 1Gb of cloud saving so you can access saved data on other PS3s, You get access to some pretty steep sales on PSN, and you get the full game trials that will let you play from where you left off if you decide to buy the game.
The other big difference is what you get for free on PS that you have to pay for with Live. If you have a 360 Live is pretty much a must. If you have a PS3 than PS+ is an add on that if you play a lot of games can pretty quickly pay for itself.









