What is the significant difference between the class system and the systems of slavery, caste, and estate?

The class system is boundless compared to the three other system of stratification-- slavery, caste, and estate. In class system, you can move up and down from the social ranking or the status you are born into. It will depend on your skills, knowledge, and effort.

While in slavery, caste, and estate, there are no movements from one group to another. Slavery is the most closed among the system. In Caste, your parents' status will be your status for the rest of your life. In an Estate system, the serfs live in poverty and are controlled by the nobility.