I believe that Wade Liles' wording in the video is confusing.
Non-adjustable drivers can be purchased with different amounts of loft. For example, the TaylorMade RocketBallz Stage 2 Tour Driver can be purchased as either a 9˚ or 10.5˚ (the options are on the right-hand side).
There are no such options for adjustable drivers like the TaylorMade R1 and TaylorMade R1 TP, they are sold as is and then can be adjusted (those models can range from 8˚ to 12˚).
So in the video when Wade says that Sergio likes 8.5, he grabs a 10˚ one from the drawer and then adjusts it to 8.5˚, but he could've grabbed any of the other heads.
To answer your question, there is no difference between tweaking a club vs using a stock loft. The reason they tweak it in the video is because you can't have a 8.5˚ R1 any other way.