Lights (supposedly) have lower nicotine and tar content. However, they don't help you quit, because you get addicted to an amount of nicotine, not a number of cigarettes (if you switch from regular Marlboros to lights, you'll just get more cravings throughout the day). And they aren't "better for you", as the tobacco and filters in light cigarettes contain more chemicals to keep them burning longer, which are equally as damaging.