Please tell me what's the diff in hycodan and hydrocodone?

Different ingredient: Both have hydrocodone, usually in 5 mg doses, but Hycodan contains homatropine, another medication used to treat cold symptoms. In high doses, homatrophine can cause severe illness and even death. If you are planning on using Hycodan instead of hydrocodone for whatever purpose (pain or abuse), excessive amounts of Hycodan can be very, very dangerous. So don't. If not, ignore the above.