What is the difference between virtualization and containerization, and name a popular container tool?

• A. It runs a single OS instance per VM
• B. It runs multiple OS instances; containers isolate apps with a shared host OS; Docker is a container tool
• C. It uses containers to run hypervisor-managed VMs
• D. It cannot isolate applications

Answer: (B)

Virtualization and containerization differ in what they virtualize and how isolation is achieved. In virtualization, a hypervisor creates separate virtual machines, each with its own complete operating system, running on the same hardware. In containerization, multiple containers share the same host operating system kernel but are isolated from each other, each containing the app and its dependencies in a lightweight, portable unit. This shared-kernel approach makes containers faster to start and more efficient, while the VM approach provides stronger, more complete isolation at the cost of more overhead.

A popular container tool is Docker, widely used to build, package, and run containerized applications.