Although many enterprises have deployed Kubernetes and containers, most also operate virtual machines. As a result, the two environments will likely co-exist for years, creating operational complexity and adding cost in time and infrastructure.
Without going into the pros and cons of one versus the other, it’s helpful to remember that each virtual machine or VM contains its instance of a full operating system and is intended to operate as if it were a standalone server—hence the name. By contrast, in a containerized environment, multiple containers share one instance of an operating system, almost always some flavor of Linux.