Docker vs. VM (Virtual Machine)

Before we start with the Docker vs. Virtual Machines comparisons, let's have a quick warm-up on these tools.

What is Docker?

Docker is popular virtualization software that helps its users in developing, deploying, monitoring, and running applications in a Docker Container with all their dependencies.

Docker containers include all dependencies (frameworks, libraries, etc.) to run an application in an efficient and bug-free manner.

Docker Containers have the following benefits:

• Light-weight
• Applications run in isolation
• Occupies less space
• Easily portable and highly secure
• Short boot-up time

What is a Virtual Machine?

A virtual machine (VM) is a computing environment or software that aids developers to access an operating system via a physical machine.

Now, let’s dig into the concept of Docker vs. virtual machine.

Docker vs. Virtual Machine

Depicted below is a diagrammatic representation of how an application looks when deployed on Docker and virtual machines

Now, let's have a look at the primary differences between Docker and virtual machines.

Differences	Docker	Virtual Machine
Operating system	Docker is a container-based model where containers are software packages used for executing an application on any operating system In Docker, the containers share the host OS kernel Here, multiple workloads can run on a single OS	It is not a container-based model; they use user space along with the kernel space of an OS It does not share the host kernel Each workload needs a complete OS or hypervisor
Performance	Docker containers result in high-performance as they use the same operating system with no additional software (like hypervisor) Docker containers can start up quickly and result in less boot-up time	Since VM uses a separate OS; it causes more resources to be used Virtual machines don’t start quickly and lead to poor performance
Portability	With docker containers, users can create an application and store it into a container image. Then, he/she can run it across any host environment Docker container is smaller than VMs, because of which the process of transferring files on the host’s filesystem is easier	It has known portability issues. VMs don’t have a central hub and it requires more memory space to store data While transferring files, VMs should have a copy of the OS and its dependencies because of which image size is increased and becomes a tedious process to share data
Speed	The application in Docker containers starts with no delay since the OS is already up and running These containers were basically designed to save time in the deployment process of an application	It takes a much longer time than it takes for a container to run applications To deploy a single application, Virtual Machines need to start the entire OS, which would cause a full boot process

Key Difference: Docker and Virtual Machine There are many analogies of Docker and virtual machines. Docker containers and virtual machines differ in many ways; let's discuss one analogy using apartment vs. bungalow.

Apartment (Eg: Containers)	Virtual machine (Eg: Bungalow)
Most amenities (binary and library) are shared with neighbors (applications)	Amenities (binary and library) cannot be shared with neighbors (applications)
Can have multiple tenants (Applications)	Cannot have multiple tenants (application)

For a more in-depth understanding, we will look at the key differences between the two below:

Docker	Virtual machine
Containers stop working when the “stop command” is executed	Virtual machines are always in the running state
It has lots of snapshots as it builds images upon the layers	Doesn’t comprise many snapshots
Images can be version controlled; they have a local registry called Docker hub	VM doesn’t have a central hub; they are not version controlled
It can run multiple containers on a system	It can run only a limited number of VMs on a system
It can start multiple containers at a time on the Docker engine	It can start only a single VM on a VMX

Docker vs. Virtual Machine: Which is a Better Choice?

A lot of people have this question, but the answer to this so far cannot be ascertained, but depending upon their configurations and advantages we could say that containers are overcoming virtual machines. The famous global researcher Gartner has predicted that by 2023, more than 50% of companies will adopt Docker containers. However, a serverless container like Docker will have a raise in the revenue from a small base of $465.8 million in 2020 to $944 million in 2024.