These terms are similar in the sense that both courier and cargo are modes of sending a parcel, they differ in more aspects. For example, as for the parcel itself to be sent, cargos usually send goods, heavy packages, clothing, materials and so on, while courier is about sending smaller items, like documents. Cargo ensures the safety of the things while couriers do not guarantee it. They also differ in the amount of time the sending of the parcels take: for cargos, delivery takes longer. Cargo services usually handle more number of things to be delivered. On the other hand, courier handles less number of packages. Note that most courier companies are also cargo companies, that is, they carry and deliver both big and small items.
