Containers vs. Virtual Machines (VMs): Unveiling the Key Distinctions

When you get into virtualization, you’ll find the two “main players” - containers and virtual machines. Containers and virtual machines are two ways to provide separate services within one platform. In the big scope of things, containers and virtual machines represent two depths of virtualization technology – software and hardware layers. 

They have unique features and characteristics, but also their differences, which we will explore in this article.

Understanding Containers

Containers involve technologies allowing them to pack and isolate applications with their runtime environment, along with all the files they need to start running the system. 

Containers are lightweight and quickly accessible when it comes to the virtualization of new applications. Contained applications are easy to move across different domains.

Containers usually consist of code, an operating system, and dependencies. This allows containers to operate on any software or hardware. Containers are built on hosted operating systems specifically, which enables containers to separate and manage storage, CPU, and other parameters.

Containers cannot be considered a new technology since they first appeared in 2013 with the establishment of Docker. Docker, in turn, is an open-source platform for the creation and management of applications inside containers.

Besides, most container runtime systems provide a hosted public repository of pre-configured containers that include many commonly used applications.

One drawback of containers as a virtualization technique is the shared host exploits, meaning using one hardware system for the multi-layered software structure. This is unfortunate because if anything goes wrong in one container and goes beyond it, the shared hardware system can be affected. While we’re on the topic, since containers’ runtimes offer pre-configured containers, using such a public item may result in acquiring specific vulnerabilities you wouldn’t otherwise have.

Containers can be used for shifting existing apps into cloud architecture, producing container-specific apps, and many more purposes.

Leading Container Service Providers

There are some leading container service providers you should know about.

Docker

Docker is the most popular and commonly used container runtime. Docker is a Linux kernel-based platform used for container development. Docker also has a public repository consisting of pre-configured software applications called Docker Hub. You can download containers from Docker Hub on your local Docker runtime.

Linux Containers (LXC)

LXC is an open-source runtime system for containers. Linux Containers is an alternative to many other container runtimes aimed to provide an accessible experience to users. Linux Containers focuses on the isolation of processes within the containerization.

RKT

RKT (or “Rocket”) is a container runtime system focused on security. Containers created with RKT don’t support insecure functions unless the user manually turns off specific settings. RKT containers address the breach in the market in the form of a focus on security other solutions seem to overlook often.

CRI-O

CRI-O is a Container Runtime Interface that supports integrating OCI-compatible runtimes. CRI-O is considered a lightweight alternative to Docker.

Exploring Virtual Machines

Virtual machines are an emulated representation of a physical computer. Virtualization made it possible for virtual machines to host their application and run operating systems, all the while interacting with a physical computer. To interact with a computer, virtual machines need hypervisor software, which helps to balance the interaction between the computers and virtual machines. Hypervisor assigns how many system resources virtual machines get (how much memory, storage, etc). It also helps to keep virtual machines separate so that they don’t interfere with each other’s functioning.

Virtual machines have software packages that resemble hardware parameters like CPU. Virtual machines also have additional software packages for running on emulated hardware. The software and hardware packages create a fully functioning snapshot of a completely operational system. These snapshots can further restore the virtual machine to a specific state. 

Virtual machines are usually of two main types: process and system. Process virtual machines promote the isolation of single methods. In contrast, system virtual machines help to isolate applications from operating systems and physical computers, which, in turn, depend on hypervisors that provide software access to hardware resources. The hypervisors also support separated virtual hardware platforms so virtual machines can run on Windows or Linux-hosted operating systems.

The most prominent hypervisors include Xen, VMware (ESX/ESXi), Microsoft (Hyper-V), and Oracle.

Virtual machines, unlike containers, provide users access to additional system resources. Therefore, virtual machines become the choice for tasks with significant file volumes. Virtual machines are also widely used in app development and testing.

Virtual machines are also indifferent to any exploits since they are characterized as isolated systems. 

Prominent Virtual Machine Providers

Some of the most prominent virtual machine providers include the following:

VMware

VMware is a public trading organization that has developed one of the leading virtualization technologies. VMware also has a hypervisor that helps manage virtual machines. VMware is considered an enterprise-level solution for virtual machines.

QEMU

QEMU is a solution that provides a powerful virtual machine solution in the form of emulated hardware. QEMU doesn’t offer any GUI, however.

Virtualbox

Virtualbox is one of the most popular solutions for virtual machines, with some additional tools for further distribution of virtual machines. Oracle owns the free architecture emulation system - Virtualbox.

Choosing the Right Solution for Your Needs

Containers and virtual machines are similar in their primary function, enabling the isolation of applications and their operation across various environments.

So that it is easier for you to discern which solution is right for you, we’ve concluded the comparison of containers and virtual machines.

​Essence

• Containers are software code packages.
• Virtual machines are simulations of physical machines aimed to divide the latter into several digital environments.

Virtualization technology

• With containers, virtualization primarily works within the operating system.
• With virtual machines, virtualization works within the physical device.

Size

• Containers are considered more lightweight.
• Virtual machines are considered more heavyweight.

Inner workings

• Containers collaborate with the operating system to utilize its resources.
• Virtual machines use hypervisors as a bridge between hardware and the operating system and using the resources that come with them.

Flexibility

• Containers are more flexible since they utilize the cloud as an intermediary for faster data exchange.
• Virtual machines are considered less flexible, with challenges associated with data migration.

Scalability

• Containers are considered to be highly scalable.
• With virtual machines, scaling is possible; however, it can be somewhat expensive in certain instances.

Management

• Containers offer less control to users over the external environment.
• Virtual machines give users more control over the whole environment.

Overall, virtual machines consume significant amounts of storage and require more hardware than containers. Containers are more accessible to scale from that perspective. However, data migration through the cloud, that’s associated with containers, has its challenges, too.

Virtual machines are more challenging to modify as they come as full-stack systems. Containers are easier to manage when it comes to the development and testing of applications.

Harnessing the Power of Containers and Virtual Machines in Tandem

What if you don’t have to choose one or the other? A scenario like this is possible, even though it might be challenging to find the practical application for both containers and virtual machines.

For example, a virtual machine can be created as an emulated hardware version. Then, the operating system can be installed within the hardware of the virtual machine. Once the OS is up and running a container runtime can be installed above it; on it, we can install containers.

Another use case for combining containers and virtual machines is creating a CI/CD pipeline. When several developers contribute code to a program, many issues would be avoided if identical writing environments were used. Containers can be deployed inside virtual machines to create similar environments, all the while controlling the resources below the OS level.