In reply to supafly:
I started off snowboarding 6 years ago, its pretty frustrating at the start, but once you have the basics is quite a quick progression from there on.
It hurts when you fall, and trust me you'll fall alot at first.
Its harder on the body too as you have to keep the board slightly tilted even on the flattest of surfaces.
Last winter I was doing a season and I decided to take up skiing. I found it very easy to start and a lot more natural. I was able to take lots of what I'd learnt from snowboarding and apply it to skiing.
I find skiing to be much easier on the body, it hurts a bit less then you fall (so long as your bindings are set correctly) And you can relax on the flatter and easier sections giving you a bit of a rest. As well as being able to skate along the flat sections being a bit of a revelation. After years of having to take one foot out of my board to get over flat sections of the piste.
Basically from my experience it boils down to
Snowboarding - Fun, tiring, designed for people that like to mess about and play on the snow. Lots of opportunitys to learn easy little tricks quite quickly. Great for off-piste, easy on a board you just float along, on skis it is very technical and hard to do.
Skiing - FAST, very fast compared to boarding, you're much more stable at higher speeds and can really blast it down the mountain. Other than straight jumps you're a bit limited.
I like both, and theres no reason you can't get very good at both over a season.