I think when something says DPG4 or some such thing it's only denoting the type of DPG it is. There've been several variations/improvements of the format in the time MoonShell has been in development.
Also DPG4 has better playback, the older versions of DPG took awhile if you wanted to rewind or fast forward, but DPG4 is instant. Also moonshell creates a preview of the video at 0:10 of the video. Also better audio.