Knowing the difference between lice and dandruff can help heal your scalp condition properly. Lice are infectious parasites and dandruff is a self-contained scalp condition. Dandruff comes from the head, and flakes off. Dandruff is due to the excessive shedding of dead skin cells from the scalp, and lice are wingless insects (small bugs) that infest the hair and scalp. The methods of prevention and treatment also vary between lice and dandruff.