Is this different then the Night Of Hunters cd (which imo wasn't very good)?

I assume it's an instrumental version of Night Of Hunters, hence the subtitle.

Wonder why mp3 only if that's the case?

Beacuse nobody will buy it. The album itself did poorly, and my guess is, they'd rather go the digital route for what is basically just an instrumental version of the album for the real hardcore fans.

I might actually prefer the instrumental version, but not as an mp3.

Just giving this first full listen at the moment. It's gorgeous, & totally slays the vocal version. It's basically background music, but very well done. Shame it's mp3 only; if any category of listeners really doesn't do mp3 it would be classical!