A hard cam is one that starts to load quickly into the draw cycle making the draw cycle noticeably harsher. Then at the break over point it usually drops very abruptly. Normally a bow with this type of cam has a very short valley. A soft cam is one that doesn't load as quickly and the draw cycle is somewhat smoother and the let off just kinda eases into it. The valley is mostly spongy and the wall isn't as solid.