Since you are form India let us take Crocin as example. This is a tablet which is powerful brand and t contains paracetamol an active pharmaceutical ingredient or actives salt. The actual medicine that works on body. The drugs that are marketed by medicines pharmacological name are called generic drugs. Crocin is branded drug. It also may be called patent drug. Because is well known OTC medicine. Another example of patent drug is Burnol and Dettol. While generic drugs can be having actual patents for innovation of product or process, brands are protected by registered trade marks. How the word patent medicines came is long history. It has nothing to do with actualpatent as defined under Indian patents act.