Difference using NVi

They're both DTS equivalents of Dolby Pro-Logic - i.e. they create a pseudo-surround from 2 channel sources - but NEO 6 Music has been honed to work best with music and Neo 6 Movie to work best with films.  These pseudo surround settings can be quite fun and it's sometimes interesting to try them with 2 channel music.  I remember finding that Thom Yorke's The Eraser was like a whole new album when I played it through the AV2 in Pro-Logic surround.  Generally it worked best with electronic music.