I've noticed for a while now when there are blu rays advertised at their sale price on places like bestbuy.com, they denote a "Dubbed AC3" audio track. Does this differ from what would normally come on a blu ray disc you would pay $20 for opposed to $10? The notation is not stamped on all of the sale price blu rays, and I am having some trouble trying to find definitive answers on AVS, audioholics, or just your basic google search.
Most, if not all, Blu-ray discs come with either a lossless DTS-HD MA or TrueHD audio track. The AC3 track would be lossy audio and would be, theoretically, inferior in terms of sound quality to the lossless track.