basically happy vs. sad sounding, although this isnt the best example...try this one
http://www.poetv.com/video.php?vid=116909

Scales are overrated anyhow.

The minor ("sad") scale uses a subset comprising the notes 1, 3, 4, 6, 8, 9, and 11 from a 12-tone chromatic scale. The major ("happy") scale uses notes 1,3,5,6,8,10, and 12. To go from minor to major one could simply remap note 4 to 5, 9 to 10, and 11 to 12.

To do this in digital audio is a bit more complex. As each instrumental sound is comprised of a basic, lowest frequency, varying harmonic overtones (multiples of the fundamental), and a bit of non-tonal transients noise, one would actually remap a lot of frequencies for each note substitution.

As you might imagine, sometimes overtones of two instrumental sounds can overlap, and voice overtones are how we can instantly identify voices, so I imagine there's a bit of discretion and fine tuning by hand at work here to keep things from sounding too synthetic.

funny, I found the major version of this a lot more "sad" than the original.

Major keys usually make me feel vaguely uncomfortable.

It's one of those things you don't have to feel bad about not really grasping because neurologists are still trying to figure it out too. As in "why we react emotionally to it".

"I'm happy about you beating it" sounds the title of a Bobby McFerrin/The Romantics/Michael Jackson mash-up

Thriller was a way better album than Bad too.

I agree.

Off The Wall was the best. Thriller has some great stuff on it but it also has The Girl Is Mine.

That boy had some problems but he sure could sing.