Lol, some of you guys understood me wrong.
Playlist is something like this:you have all your music(more than 1 file) in 1 .nds file which, when you run it, shows a list to choose which file you want to play.
.mp3 -> .nds will be something like this(possibly works only with nds multiloaders): for every music file there will be 1 .nds file it is saved in.
There are no extra features in one more than the other, and there is no file size differences( 5 4mb .nds files = 1 4mb .nds file)
If you have other ideas, post them!