1. The main social contradictions are different. In slave society, slave class and slave owner class are two basic classes of society, and the main contradiction in society is the contradiction between slave owner and slave; In feudal society, the peasant class and the landlord class are two basic classes of society, and the contradiction between them is the main contradiction of society.

2. Different economic bases. Slave society was built on the economic basis of slave owner ownership, while feudal society was built on the economic basis of landlord class ownership.

3. The status of farmers and slaves is different. In slave society, slaves have no personal freedom at all, which is the personal wealth of slave owners. In feudal society, although farmers were severely oppressed, compared with slaves, their personal freedom was very limited.

4. Different levels of productivity development. The development level of slave society is very underground, and the surplus wealth is very scarce. Therefore, slaves are often killed or have little living resources. The productivity of feudal society should be further developed and the surplus wealth should be further increased. Although the resources obtained by farmers are scarce, they can basically meet the needs of survival, so they are no longer killed as slaves.