What is the difference among deadlock avoidance detection and prevention?

Deadlock prevention is the name of the technique that is designed to get rid of deadlocks by changing the specifications of the system , that is the system design change. This is , basically , about how requests about resources are made and how they are permitted.

However , deadlock avoidance is a technique that aims to check deadlock possibility dynamically and decides whether it is safe to grant a resource or not. It ,definitely , needs extra information about potential use of resources for each process. Deadlock Prevention: Preventing deadlocks by constraining how requests for resources can be made in the system and how they are handled (system design). The goal is to ensure that at least one of the necessary conditions for deadlock can never hold. Deadlock Avoidance: The system dynamically considers every request and decides whether it is safe to grant it at this point, The system requires additional apriori information regarding the overall potential use of each resource for each process. Allows more concurrency. Similar to the difference between a traffic light and a police officer directing traffic.