What is the difference between the permissibility of selling a camel for two camels on credit and the prohibition of lending a camel to be returned as two camels? And is the meaning the same as the prohibition of Bay' al-'Inah, in that it is a loan with interest?

It is permissible to sell a camel for two camels at a later date, according to the majority of scholars. They cite as evidence the narration by Abdullah ibn Amr ibn al-Aas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) bought a camel for two or three she-camels on credit. However, it is not permissible to lend a camel on the condition that the borrower returns two camels, because a loan differs from a sale in intention and objective. A loan aims at assistance and benevolence, whereas a sale aims at exchange and profit. Therefore, any stipulated increase in a loan renders it usury (riba).