kubectl apply vs kubectl create?

What I understood by the documentation is that:

• kubectl create
  

  Creates a new k8s resource in the cluster

• kubectl replace
  

  Updates a resource in the live cluster

• kubectl apply
  

  If I want to do create + replace (Reference)

My questions are

1. Why are there three operations for doing the same task in a cluster?
2. What are the use cases for these operations?
3. How do they differ from each other under the hood?