A container is not a VM. It's a process with its own filesystem, network, and resource limits — running on the same kernel as the host.
Virtual Machine: Container:
┌─────────────────┐ ┌─────────────────┐
│ App │ │ App │
├─────────────────┤ ├─────────────────┤
│ Guest OS (Linux) │ │ Container Runtime│
├─────────────────┤ ├─────────────────┤
│ Hypervisor │ │ Host OS (Linux) │
├─────────────────┤ ├─────────────────┤
│ Host OS │ │ Hardware │
├─────────────────┤ └─────────────────┘
│ Hardware │
└─────────────────┘
500MB-2GB overhead 10-50MB overhead
Minutes to start Milliseconds to start