Containers vs. Virtual Machines: What’s the Difference?

As telecom and IT infrastructures evolve, two technologies dominate the discussion: Virtual Machines (VMs) and Containers. Both enable efficient use of hardware resources, but they approach virtualization in very different ways. Understanding their differences is key when deciding how to design and deploy modern network functions.

What is a Virtual Machine?

A Virtual Machine (VM) emulates an entire computer system. It runs on top of a hypervisor and includes its own full operating system (OS) and applications. Multiple VMs can share a single physical server, each isolated from the others.

Pros:

• Strong isolation between workloads.

• Mature ecosystem with robust management tools.

• Can run different OS types on the same host.

Cons:

• Heavy: each VM requires its own OS, consuming significant CPU and memory.

• Slower startup compared to containers.

• Less efficient in high-density environments.

What is a Container?

A Container is a lightweight, portable unit that bundles an application with its dependencies (libraries, runtimes, configs). Unlike VMs, containers share the host OS kernel, making them much smaller and faster. They are typically orchestrated by platforms like Kubernetes.

Pros:

• Lightweight, allowing higher density on the same server.

• Extremely fast startup and shutdown.

• Ideal for microservices and cloud-native applications.

Cons:

• Weaker isolation compared to VMs (since they share the host OS).

• Requires strong container security practices.

• Less suitable for running different OS types on one host.

Containers vs. VMs – The Key Difference

• VMs virtualize hardware, making them look like separate machines.

• Containers virtualize the OS, allowing applications to run in isolated environments while sharing the same kernel.

In practice:

• VMs are best when strong isolation, multi-OS support, or legacy applications are required.

• Containers are best when agility, scalability, and efficiency are the priority — especially in cloud-native and 5G environments.

Conclusion

Containers and VMs are not mutually exclusive — they are often used together. VMs provide the underlying infrastructure with strong isolation, while containers run lightweight, flexible applications on top. In telecom, this hybrid approach is common: VMs for VNFs, and containers for CNFs. Choosing the right mix depends on workload requirements, security needs, and performance goals.