Panthermark is spot on.
As the Rubicon is meant to be the most offroad capable of all Wranglers, it comes with the most offroad oriented features--thus the lockers.
And the type of locker that is standard equipment in the Rubi is mutually exclusive of the type of LSD that is optional on the Sport/Sahara. There's only room for one in each differential ("pumpkin").
For this reason, an LSD-equipped Sport/Sahara is in truth a better winter weather vehicle than a Rubicon. An LSD is useful on and off the trail, whereas a locker is really only useful on the trail.
That's just one of the trade offs you make when buying a Rubi. Others include, for example, the gas mileage hits you take getting standard mud tires and 4.10 differential gears.
Originally Posted by LoCo Jeep
So a Rubi in 2WD is the same as my sport?
Depends on what you mean by "the same."
The Rubi will likely have 4.10 gearing and mud tires, neither of which (in its stock form) will be possessed by your Sport.
But if you're speaking only about traction assistance, then the answer is "yes."