In the American colonies of the 17th and 18th centuries, both slaves and indentured servants filled the need for a cheap source of labor for farms and plantations of rice, tobacco, indigo, and other crops. Both forms of labor were unpaid and both slaves and indentured servants were subject to mistreatment, unfavorable working conditions, and harsh forms of punishment. However, there were also profound differences between the lives of slaves and indentured servants.
Indentured servants were mainly people brought over from Europe for fixed periods of contracted time that varied from four to seven (or more) years. Their masters paid their fares across the Atlantic in full and provided them with room and board. This was not slavery, though, because at the end of their terms of contract, the indentured servants would be free citizens. Their masters typically supplied them with termination pay that might include land, food, weaponry, and clothes.
In fact, the first Africans brought to Jamestown in the early 17th century aboard a Dutch trading ship were given indentured servant status and eventually became free.
Due to financial expediency, slavery replaced indentured servitude in the Deep South and, to a lesser extent, throughout the rest of the American colonies. Slaves, unlike indentured servants, were treated like property. They received basic food and shelter and were forced to work long hours. They had no rights and received no education or freedom of movement. They had to obtain their master's permission before they were allowed to marry or have children, and at any time, their masters could buy and sell them, separating families in the process.
In conclusion, both slaves and indentured servants were subject to oppression and harsh treatment, but indentured servants were people in temporary service who would afterwards regain their freedom, while slaves were considered property for the duration of their lives and were rarely ever granted freedom.