"It's luge — backwards" is the simplest way I've heard the skeleton event explained.

“It’s luge — backwards” is the simplest way I’ve heard the skeleton event explained.

This describes the most obvious difference: lugers ride on their backs with their feet pointed down the track while skeleton racers are headfirst on their bellies.

But it’s a little more complicated than that.

For a regular snow-day sledder, the luge sled could compare to a toboggan on tracks: higher off the ground with an upturned bow. The skeleton sled is rectangular and lower to the ground — a magic carpet on ice, if you will.

Aerodynamics is key in both sports. Lugers wear pointed booties to increase speed, while skeleton racers’ helmets extend under their chin. The helmet shape is so critical that the U.S. team filed a protest against British racer Amy Williams, claiming ridges on her helmet gave Williams an aerodynamic advantage. The protest was declined late Thursday.

Women’s skeleton kicks off this afternoon with men’s races following tonight. Germany and Canada are favored in both men’s and women’s. Latvia’s men’s team is strong while Great Britain has top contenders in women’s races.

Check out graphics of skeleton and luge for in-depth explanations of the two sports.

More visual guides to Olympic sports and venues.

Seattle Times multimedia producer Daniel Gawlowski contributed to this report.