Singles are songs that are not on an actual album, but can be bought separately, usually (in the case of Meg and Jack) on 7" vinyl.
Live songs are songs that are only played live and have yet to be released as a single or on an album. Like "Boll Weevil" which is typically played at the end of every concert.
If this community grows a lot, which I think it will, you may want to also offer live versions of songs that are both singles and songs on the albums, such as the SNL performance of Dead Leaves on the Dirty Ground or the 11/22/03 performance of Let's Shake Hands (which I am madly in love with since I went to that show.)
Those are just suggestions. I hope you found them helpful!
Have A Nice Day,