No, it's not what you are thinking, let me tell you why? Virtual machines have a full OS with its own memory management installed with the associated overhead of virtual device drivers. In a virtual machine, valuable resources are emulated for the guest OS and a hypervisor, which makes it possible to run many instances of one or more operating systems in parallel on a single machine or host. Every guest OS runs as an individual entity from the host system.
Now talking about Docker, So Docker containers are executed with the Docker engine rather than the hypervisor. Containers are therefore smaller than Virtual Machines and enable faster startup with better performance, less isolation and greater compatibility possible due to sharing of the host’s kernel. If you want to know more about these things, then you must have a look at the following Docker Tutorial. If you want to make your career in the field of cloud computing using Docker then you must take up the following Docker Training Course which is specially designed for an absolute beginner/intermediate/working professional. Here is the video by which I came to know many important things about Docker. .