Two DVD versions of the series?

Alright, first off, as a musician and a huge fan of music in general I absolutely love this show. I downloaded it a few days ago and I finished watching the series at about 5:30 this morning.

I intend to buy the series on DVD once I have the disposable income to do so, but there seem to be two different sets that contain the entire series.

One (which is a 6-disc set) has a sort of montage on the cover consisting of an image from the opening theme where the band's playing in front of what I always assumed was a diner, and another image of Ryuske, Yukio and Maho.

The other set has 4 DVDs and is apparently referred to as "The Viridian Collection." The cover is a picture of Yukio performing, with a look on his face reminiscent of the cover of Radiohead's album The Bends.

Does anyone know the exact differences between these two sets (special features, censorship, et cetera) and is one recommendable over the other?

God has a hard-on for Marines, because we kill everything we see.