Similarities between the ecomienda and slavery in the Spanish colonies

Encomienda system posed a requirement of a group of individuals to give back to another in work, kind or otherwise, in exchange for a good received. It was established that a person who received the legal right to be an encomendero, had at his disposal a village of Indians with his caciques to pay him tribute and to serve him. In return, the Indians received "protection", that is to say, the encomendero had to take care of the well-being of the natives in the spiritual and in the earthly thing, assuring its maintenance and its protection, as well as its Christian indoctrination (evangelization).
The figure of the cacique or main character of the towns was very important because he used to be the intermediary between the encomendero and the Indians. The population was supposed to pay the Crown so the caciques collected the valuable things from their population and gave them to the encomendero.
This system differs from slavery inasmuch as it is considered as a system of exchanges where both parties give something in exchange for receiving something, in slavery there is no guarantee of anything to people, and they are only subjected to doing things for the sake of force. However, the encomienda has resembled slavery or has derived in it, since there have been abuses where forced labor, mistreatment and other things to the indigenous people ended up being imposed. On the other hand, encomienda as well as slavery is a system imposed. Another similarity is that the natives had to serve the encomendero, his family or whom they wanted to serve, in a mandatory manner. Also, both in the system of entrustment as in slavery, the people subjected do not have liberties, in the system of encomiendas you do not have the freedom to choose not to pay the crown since it is established as a duty and obligation, as well as they lose their freedom by being under the orders of the encomendero. In slavery, people also can not choose and must follow orders. But it should be mentioned that in the encomienda Indians could be entrusted for a maximum of 2 years, could not establish a perpetuity as dictated by the crown, different from the people subjected to slavery that were considered a more "economic" labor, they were forced to perform tasks under someone's command for indefinite periods, that is, there was a perpetuity of slavery that lasted as long as the person submitting them wanted, since in slavery one person (the master) takes over another ( the slave).

Is this the whole problem or