Containers vs. VMs: Similarities, differences, and combined approaches

Containers and virtual machines (VMs) are different approaches to packaging computing components and isolating them from the rest of the system. The main difference lies in what components are isolated, which in turn affects the scale and portability of each approach. 

Both containerization and virtualization are mature, well-supported IT technologies. They can work together in many architectures, serving different application needs. Modern application platforms, including Red Hat® OpenShift®, support both types of technologies, encouraging flexibility.

Open Answers: How are VMs and containers different? Video duration: 0:36

Explore Red Hat's virtualization solution

A container is a unit of software that holds together all the components and functionalities needed for an application to run. Unlike a virtual machine, a container doesn’t require a guest operating system. Most modern applications are made of multiple containers that each perform a specific function. 

A container packages an application and its dependencies together in a portable unit. You can deploy the container anywhere needed—a developer laptop, a datacenter, a cloud environment, or the edge—with the expectation that it will maintain consistent behavior and functionality. 

Compared to VMs, containers are typically smaller (measured by the megabyte). Their smaller size makes them a faster and more agile way to scale to match changes in demand. 

With their portability and consistency, containers are important to modern cloud-native software development, including DevOps and continuous integration and continuous delivery (CI/CD) practices. They let you split applications into functions and microservices. Compared to traditional architectures, this simplifies scalability and movement of IT projects across diverse IT environments.

With containers, different teams can work on individual parts of an application or service without interrupting or threatening code packaged in other containers. A modern application might rely on hundreds of containers loosely coupled together. Teams manage these large fleets of containers with a container orchestration platform such as Kubernetes (which is the foundation of Red Hat OpenShift).

Containers also have security and resilience advantages over VMs. Using containers minimizes an environment’s attack surface (a vulnerability in 1 container is isolated from other parts of the application) and prevents configuration drift. Containers are short lived, lightweight, and frequently rebuilt from version-controlled sources. Additionally, their declarative and consistent nature enhances transparency for software teams, allowing easier vulnerability scanning compared to traditional environments and streamlined, automated security controls.

Read more about containers

A VM is an isolated computing environment with its own CPU, memory, network interface, storage, and operating system, emulating physical computers. Multiple VMs can run on a single server, with a hypervisor acting as a lightweight software layer positioned between the physical host and the VMs. This hypervisor efficiently manages access to resources, allowing VMs to function as distinct servers for greater flexibility and agility.

By placing many VMs on each physical server, traditional virtualization technology can make better use of hardware, leading to cost savings. This orchestration abstracts physical resources (typically compute, network, and storage) so users can access them through software.

VMs have served as the foundation of many early cloud computing environments, facilitating resource virtualization and supporting multi-tenancy and isolation where multiple users can run systems that share the same resources. Additionally, because VMs contain their own operating system, they can perform various resource-intensive functions at once, allowing them to abstract, split, duplicate, and emulate entire servers, operating systems, desktops, databases, and networks.

With VMs, workloads that were traditionally bound to on-premise servers can run in cloud environments or in hybrid cloud configurations. This gives IT organizations even more flexibility to run workloads where they’re most efficient and manage costs.

Read more about virtual machines

Using containers unlocks the advantages of cloud-native applications, including scalability, efficiency, and automated lifecycle management. 

What if you could manage VMs the same way? Open source projects like KubeVirt make it possible to run VMs side by side with containers. You can apply a consistent set of modern tools on a unified platform to manage both containers and VMs. Benefits of this include:

Unified cloud-native administration

• Reduce complexity and encourage cooperation among teams by managing VMs, containers, and serverless workloads on a single platform.
• Simplify administration with cloud-native tooling such as CI/CD pipelines, monitoring, and automation.
• Align VM administrators and DevOps team members with consistent processes for deployment, scaling, and lifecycle management.
• Allow self-service VM provisioning with standardized workflows and templates.

Scalability

• Run VMs across different infrastructure, including in on-premise, cloud, and edge environments.
• Dynamically scale cloud resources to meet demands for VM workloads.
• Reduce infrastructure costs and use your resources as efficiently as possible by consolidating VMs and containers on 1 platform.

Simplified AI integration

• Introduce new AI services incrementally without disrupting your existing VM workloads.
• Build, train, and deploy artificial intelligence and machine learning (AI/ML) models on the same platform as your current applications and data.
• Take advantage of AI-ready infrastructure to power more intelligent automation, data insights, and new AI applications.

Modernizing on a cloud-native platform can be a complex journey. But in the end you’ll operate more productively and efficiently, waste fewer resources, and expand opportunities for future innovation.

Read about application modernization on Red Hat OpenShift

Is OpenShift Virtualization right for your VMs? Video duration: 1:57

Develop, modernize, and deploy containerized applications at scale

Red Hat provides enterprise platforms for container and VM deployments across a variety of environments. Red Hat OpenShift is a modern application platform that brings together a comprehensive set of tools and services that streamline the entire application lifecycle—from development to delivery to management of application workloads.

Migrate your VMs and maintain your momentum

Red Hat’s trusted products and partner ecosystem deliver comprehensive virtualization solutions. You can migrate your VMs to Red Hat OpenShift Virtualization, a modern application platform—based on KVM and KubeVirt—that integrates virtual and containerized workloads to provide flexibility without added complexity. For a dedicated virtualization solution, Red Hat OpenShift Virtualization Engine offers a streamlined, cost-effective way to deploy, manage, and scale VMs exclusively. Red Hat’s migration toolkit for virtualization gives you the tools to start your migration in just a few steps.

Red Hat OpenShift Virtualization is available through our cloud partners, including AWS, Microsoft Azure, Google Cloud, IBM Cloud, and Oracle Cloud Infrastructure.

Automate your migration

Use automation to speed software delivery with Red Hat Ansible® Automation Platform—from migration at scale to Day 2 operations and remediation. With this flexible approach, you can automate tasks to improve speed and efficiency of IT operations.

Manage and modernize at your own pace

Monitor the security and performance of your VMs from a single console with Red Hat Advanced Cluster Management. With additional support options and partner integrations, you can rely on Red Hat to keep your virtual infrastructure running smoothly throughout your hybrid cloud environment—and help you modernize when you’re ready.

Explore our virtualization solution