In what ways does the current FAA written exam differ from the Sporty's practice test?
I took the PPL written exam this morning (9/30/2016), but I used the Jeppesen PPL materials to prepare. Although I cannot speak to the Sporty's study materials, the Jeppesen practice exam and supporting materials were identical to the questions on the real exam. I would assume that Sporty's will be (almost?) the same. I actually scored higher on the real exam than on any of the practice tests.

Yes, the current exam uses the Airman Knowledge Testing Supplement for Sport Pilot, Recreational Pilot and Private Pilot booklet.