Is there any real difference between a $50 helmet and a $150 helmet?

I'd rather save some money if the cheaper option is as or almost as safe as the more expensive one.

Edit: From these few answers already I've decided that I'll take a cheaper helmet if it's comfortable and ventilated enough for me :) My old helmet broke in a crash (nothing haopened to me) and it was a cheap helmet, so now I was just wondering if I should get a more expensive one for more safety :P