Lightscribe is a special coating at the top.
After you have burnt the data onto the disc, you pull the disc out, flip it over & burn your title / piccies onto the top of the disc.
Lightscribe discs are the same as the NON-lightscribe discs, except for that special burnable coating.
If you don't have lightscribe, or don't ever intend using it, it's a great way to double your disc prices, and waste your money.
Especially when you can get the silvertops (the cheapest) or the inkjet printables (cheap printers are available these days). And either of these can be written on with a sharpie (permanent marker).