foam is lighter just as strong and more reliable............ for the first lil bit....... then the chemical bonds holding the foam together deteriorate and ur left with a flacid soft non responsive ski after 3-16 months (depending how hard you ride). wood weighs a lil more but will not deteriorate it will stay just as strong forever and its more springy. and its natrual so if you get lost in the woods for a long time you can eat ur skis core, i hear the poplar cores in lines can be quite good with some A.1. steak sauce Im not a fan of foam cause to me its a cheap tricky marketing sceme, people demo foam core skis love em, buy em, they get soft and the ski sucks and its artificial