Aside from movie studio exclusives support, the main differentiating factor between the formats is storage space. In their current market iterations, Blu-ray Discs hold a 20GB advantage with its dual-layer 50GB media when compared to HD DVD's dual-layer 30GB discs.
Sony realizes this distinct advantage, and is committing to rolling out 80 percent of all its forthcoming Blu-ray titles as 50GB discs, according to Video Business.
When transferring a film onto Blu-ray, compression engineers may utilize the extra 20GB to attain higher bit rate video and to accommodate lossless audio streams. While many dual-format releases of late, such as The Departed, feature identical video streams encoded with the same codec, engineers recognize that the added space afforded by Blu-ray can be spent to improve quality.