Kubernetes vs Swarm

• Kubernetes is a more mature and powerful orchestration tool than Swarm. Swarm provides basic and essential native clustering capabilities. But Kubernetes has built-in self-healing, service discovery (etcd), load balancing, automated rollouts and rollbacks, etc. Building all these functions on Swarm is not trivial. However, this may or may not be a good thing depending on use cases. If you do need all the features that Kubernetes provides and don't intend to do any customization, Kubernetes is perfect for you. Otherwise, the complexity of Kubernetes might become a burden because it requires more efforts to adopt and support.
• Different philosophies. Kubernetes has clearly taken an all-in-one approach, while Swarm is batteries included but swappable. So if I want to use Consul as the service discovery backend, I can easily do that in Swarm. But Kubernetes uses etcd by default and it's still not supported after more than one year..
• Kubernetes is primarily based on Google's experience on managing containers. So it's opinionated by definition. I'm not saying being opinionated is necessarily bad. But if you do decide to use it, you probably have to live with its choices. Consul is just one example.
• Command Line. Unlike Swarm, Kubernetes is not native to Docker. It has its own set of commands. See the the differences here. But in general, kubectlis quite similar to docker-cli.
• Swarm performs better than Kubernetes. I think this only matters when you are running hundreds or even thousands of nodes and containers. At a small to medium scale, other factors (e.g the points above) play a more important part when deciding which one to use.