Docker : Its an open source platform that provides ways to run application in an isolated containers, it provides lightweight env which encapsulates application and its dependency.
Docker host individual application containers, setting up network connection, security and storage of each container needs to be handled manually
Kubernetes : Kubernetes is an open source platform which provides framework for automating deployment, scaling and management of containerized application accross cluster of nodes.
Kubernetes host multiple docker containers across nodes. It works at cluster level.
K8 framework provides automated ways to setup storage, network and security policy.