What is the difference between servants and indentured or enslaved people?

A servant is paid for his or her work and can quit at any time.

An endentured servant has a contract calling for him or her to provide service for a specified number of years and cannot leave until that time is passed. The contract, or indenture, may provide for some forms of payment to be made, or merely for room and board to be provided if the indenture was agreed to in exchange for something substantial such as transportation to the "New World." The children of an indentured servant are not bound by the terms of the contract.

An enslaved person, a slave, is property and must work for the owner, just like a horse or other animal property. The slave can never leave and the children of a slave is also slaves just as the foal of a horse you own is also your horse.