Nomad vs. Kubernetes
Kubernetes is an orchestration system for containers originally designed by Google, now governed by the Cloud Native Computing Foundation (CNCF) and developed by Google, Red Hat, CoreOS and many others. Kubernetes aims to provide all the features needed to run Docker or Rkt-based applications including cluster management, scheduling, service discovery, monitoring, secrets management and more.
Nomad only aims to provide cluster management and scheduling and is designed with the Unix philosophy of having a small scope while composing with tools like Consul for service discovery and Vault for secret management.
While Kubernetes is specifically focused on Docker, Nomad is more general purpose. Nomad supports virtualized, containerized and standalone applications, including Docker. Nomad is designed with extensible drivers and support will be extended to all common drivers.
Kubernetes is designed as a collection of more than a half-dozen interoperating services which together provide the full functionality. Coordination and storage is provided by etcd at the core. The state is wrapped by API controllers which are consumed by other services that provide higher level APIs for features like scheduling. Kubernetes supports running in a highly available configuration but is operationally complex to setup.
Nomad is architecturally much simpler. Nomad is a single binary, both for clients and servers, and requires no external services for coordination or storage. Nomad combines a lightweight resource manager and a sophisticated scheduler into a single system. By default, Nomad is distributed, highly available, and operationally simple.
Kubernetes documentation states they can support clusters greater than 5,000 nodes and they support a multi-AZ/multi-region configuration. Nomad has been proven to scale to cluster sizes that exceed 10,000 nodes in real-world production environments. Nomad also natively supports multi-datacenter and multi-region configurations.