like said above:
a board has some disadvantages - it has only one edge to grip into the snow and is less fast - and has no safety-bindings.
another cool feature of skiies is:
you can move around without removing them.
(removing one foot of the snowboard to change position to the kite (for example to restart) is very dangerous - it coulld kill your knee)
if you take a snowboard and set the bindings to TT-style you'll be able to just start and ride like it's water and u use your board.
right in the moment i use neither board nor ski, but go surfing