What is the difference between judging and validating a workout?

Judging involves watching the athlete perform the workout and ensuring that the athlete completes all of the reps according to the standards outlined on the CrossFit Games site. Anyone can be a judge during the Open. However, for any top athlete who has a chance at advancing past the Open it is strongly recommended to use a judge who has passed the Online Judges Course. Athletes competing at the next stages of competition are required to use a registered judge as well.

Completing the Judges Course will make you a registered Judge for the season. 

Validating involves approving a score submitted by an athlete. Only the Affiliate Manager can validate scores. The Affiliate Manager is either the affiliate owner, or a person delegated by the affiliate owner. The Affiliate Manager has passed the Online Judges Course, committed to upholding the standards and ethics of the CrossFit Games, and asserted that they have the equipment, facility, and judges necessary to administer the workout. By validating the score, the Affiliate Manager gives the score the affiliate's stamp of approval.

Here's how the process works. All competitors have two options: They can either (1) film the workout and submit their score and video to the CrossFit Games site, or they can (2) complete the workout at a participating affiliate in front of a judge. If they chose to complete the workout at an affiliate, a  judge will watch them through the entire workout and assure that they meet the standards. The athlete will then be responsible for submitting their score on the Games site before Monday at 5 p.m. PT. As part of the score submission process, the athlete will state where they completed the workout. The Affiliate Manager from that particular affiliate will then need to validate the score in order for it to appear on the Leaderboard.