From what I understand, Kubernetes/Mesosphere is a cluster manager and Docker Swarm is an orchestration tool. I am trying to understand how they are different? Is Docker Swarm analogous to the POSIX API in the Docker world while Kubernetes/Mesosphere are different implementations? Or are they different layers?
Swarm is a very simple add-on to Docker. It currently does not provide all the features of Kubernetes. It is currently hard to predict how the ecosystem of these tools will play out, it's possible that Kubernetes will make use of Swarm.