The banana magic is definitely an all mountain board. It will be stiffer and not as forgiving. It is a great board though I ride the T Rice which is similar and it is the best board I have rode. The BM uses C2 which means it has the normal banana in between your feet and then is cambered under your feet. Riding c2 can take some getting used to but it is really nice when going off of any kind of jump (delivers amazing pop). BM also uses horsepower I have not rode this but lib tech seems very excited about it and it is suppose to give the board a much damper ride. I would say the BM is a intermediate to advanced board it will be great in the powder but also nice in the groomers. Keep in mind it is a stiff board and may take a few days of riding to get used to. All in all it is a great board.
The Skate Banana is a much softer board it uses a reverse camber set up making it very good in powder because it is able to float on top. This board is very forgiving because it is softer making it great for a beginner or and intermediate rider. It would be a great park board or good all mountain board as long as you stay inside the boundaries can handle any run green to black. Will not be the best board at high speeds but will preform and get the job done. Both boards uses magne traction which is a waved edge allowing seven contact points between you and the snow. This is great for ice days and gives you much more control and confidence on ice.
Both these boards are very nice. Lib Tech does a great job with their produces and they make some of the best boards around. If you would give a little more info on what type of rider you are it would be easier to tell what board would suit you best.