Basically, the PS Plus Edition of DRIVECLUB is just a small bit of what you get in the retail edition. Think of it as an expanded demo, but one that plays like a full game and even has trophies you can earn. It will come with one location (India), 11 tracks, 10 cars and access to all game modes. This will all be free for PS Plus members when it is released. If you decide that you want to upgrade to the full version of DRIVECLUB, you can do so by unlocking it for $49.99. This will include all five locations, 55 tracks, 50 cars and all 50 tour events, as long as your PlayStation Plus subscription remains active.
Of course if you don’t have PS Plus or don’t want to be tied down to it in the future, I suggest picking up the retail copy of the game which includes everything without the PS Plus strings attached, though you’ll probably need it to play online.