As of this writing I have only previewed each disc in the collection. "Planet Earth" comes w/4 discs and is displayed in 1080 Progressive Scan. The remaining discs in the collection are in 1080i, however, I can see no remarkable difference. There is, however, a marked difference between DVD and Blu-Ray. This collection needs to be seen in Bluray to fully appreciate it's potential. So far, all discs are of the highest quality and interestingly narrated; As good as, or better, than the very best nature documentary one has ever seen on television. Well worth the price for the amount of high-quality footage (over 1000 minutes); Can easily be viewed more than once, especially by children...There is no price difference whether you buy these sets individually or in this box set---this way, though, they come in their individually marked plastic cases, and all 4 boxes fit into the pictured cardboard case.