The reason why it was very hard for you to snowboard was probably because you are used to skiing. Skiing just feels different, in my opinion, it feels better. Your legs can operate separately, so IMO it feels more normal. Same thing happened to me. I consider myself an expert skier, but when I snowboarded for the first time, I fell 7 times or so on the 100 ft long bunny slope. I'm a decent snowboarder now, I can carve on the greens, but I will never EVER go on a black.