Sleds are typically smaller and simpler than sleighs, though this is not always the case.
With only gravity as the propelling force, a sled can be used downhill, also as a toy.
Alternatively, it may be pulled by animals, usually horses or dogs. It may also be pushed or pulled by humans (playing children, a parent pulling a child, etc.).
A troika is a vehicle drawn by three horses, usually a sled, but it may also be a wheeled carriage.
The fictional flying sleigh[?] of Santa Claus is pulled by flying reindeer. It involves little sliding, perhaps only during taking-off and landing.
The various categories of sleds include:
wikipedia.org dumped 2003-03-17 with terodump