The "Lite" version of the elevator kit is an entry-level kit aimed at users who have no need for big elevator cars that are capable of traversing many floors. The Lite kit contains the Firefly elevator car which is limited to 4 floors and is much smaller than its bigger brothers. It also does not have a floor indicator LED and has a single sliding door instead of two.
The Lite doors are smaller than the standard doors to fit the Firefly car. They also do not have a floor indicator LED or directional arrow indicators.
This kit is ideal for residential installations and is what it was designed for. It has only the basic features at a good price.
You can buy it in-world or at SL Exchange:
http://www.slexchange.com/modules.php?name=Marketplace&file=item&ItemID=527935