Docker Container vs Virtual Machine — What's the Difference?

A virtual machine virtualizes an entire computer, including its own full operating system kernel; a container virtualizes only at the application level, sharing the host machine's kernel while isolating processes and filesystems.

Why they differ

• VMs are heavier — each one runs a full guest OS, using more memory and taking longer to start
• Containers are lightweight since they share the host kernel, starting in seconds and using far less overhead per instance

How to choose

• Use containers for packaging and deploying applications consistently across environments with minimal overhead
• Use full VMs when you need to run a genuinely different operating system, or need the stronger isolation boundary a separate kernel provides

FAQ

Are containers less secure than VMs?

Containers share the host kernel, so the isolation boundary is generally considered weaker than a VM's — a kernel vulnerability could theoretically affect all containers on a host, which isn't the case across separate VMs.