What is the difference between Lortab and Vicodin, and also Darvocet?

Lortab always has 500 mg of tylenol in it. 5/500, 7.5/500 and 10/500. Vicodin comes in three forms, 5/500, 7.5/750 and 10/650. The only difference between vicodin and lortab is the amount of tylenol. Darvocet is a much milder narcotic pain reliever.