By the contract of loan, one of the parties delivers to another, either something not consumable so that the latter may use the same for a certain time and return it, in which case the contract is called a commodatum; or money or other consumable thing, upon the condition that the same amount of the same kind and quality shall be paid, in which case the contract is simply called a loan or mutuum.
Commodatum is essentially gratuitous.
Simple loan may be gratuitous or with a stipulation to pay interest.
In commodatum the bailor retains the ownership of the thing loaned, while in simple loan, ownership passes to the borrower. (1740a)