Skiboards are generally 80-120 centimeters long, symmetrical, twin tipped, and wider than traditional skis. Snowblades is a trademark of Saloman, but essentially snowblades are skiboards.
1990, Austrian company Kneissel introduced the BigFoot, a 65 centimeter, foam-injected ski with a binding system. Some consider the BigFoot to be the first mass-produced skiboard. Next came the MicroSki, created by Kent Keiswieller in 1992. Then Snowblades.
You can see the variance here:
http://www.ifyouski.com/Gear/Skiboard/
.