Virtual Machines vs Containers: Understanding the Difference
Virtual Machines (VMs) and containers are both technologies for isolating and running applications — but they work differently, have different trade-offs, and are suited to different use cases. Understanding the difference helps explain many of our infrastructure decisions.
Virtual Machines
A virtual machine emulates a complete physical server — including its own operating system kernel, hardware drivers, and full OS. VMs are created by a hypervisor (VMware, Hyper-V, KVM) that runs on physical hardware. Each VM includes a full OS, making it large (gigabytes) and slow to start (minutes). VMs provide strong isolation — each has its own kernel, memory space, and resources.
Containers
Containers share the host operating system kernel but isolate their processes, filesystems, and network interfaces using Linux kernel features (namespaces and cgroups). A container image is typically tens or hundreds of megabytes and starts in seconds. Containers are more lightweight than VMs — you can run dozens of containers on a server that would host only a handful of VMs.
Practical Differences
| VMs | Containers | |
|---|---|---|
| Start time | Minutes | Seconds |
| Image size | Gigabytes | Megabytes |
| Isolation | Strong | Good (not kernel-level) |
| Overhead | High | Low |
| Best for | Full OS isolation needs, Windows workloads | Microservices, applications, CI/CD |
Our Approach
We predominantly use containers (Docker) for application workloads and run them on managed container services (ECS, EKS, Cloud Run) — combining container flexibility with cloud-managed operations.