What is the main difference between indentured servants and slaves?

Answer: 4th question down I think :)
Explanation:
according to https://cliveden.org/discover-cliveden/slavery-and-servitude/#indentured,
"The rights to the individual’s labor could be bought and sold, but the servants themselves were not considered property and were free upon the end of their indenture (usually a period of five to seven years). "