In a short one line i can describe like below
- – Bare metal – Deploying a new version of Windows to a system that currently has nothing installed on it.
- – Refresh – Wiping an existing system and deploying a new version of Windows to it migrating any user settings and data that need to be kept.
- – Replace – Replacing an existing System with a new one by installing a new operating system on the new computer and then optionally transferring over any user settings and data that need to be kept from the old System
- – Upgrade – Upgrading the existing operating system from Window 7, 8.x to 10 whilst retaining all of the existing applications, settings and user data that is already on the computer.