User blog comment:Canvasofgrey/A New View on Supports v.1.1/@comment-4834593-20120421122623/@comment-4636093-20120421134844

Kill lanes are lanes with a powerful early game AD carry like Ezreal and a support with hard CC like Alistar or Taric. The goal of them are to go mega harrass and kill the enemy early or at least push them away from the lane to deny them farm.

Farm lanes, or passive lanes, just want to farm, they never want to engage until late game when they go uber hyper carry. Vayne for example will just farm for the first 20 minutes of the game, with a Soraka support to heal her up and keep her in the lane for as long as possible.