Windows manages hardware, apps and drivers. Home suits everyday use and gaming. Pro adds management features such as hosting Remote Desktop and fuller BitLocker controls. Check the edition and activation status before buying a used PC. A motherboard replacement can affect activation, depending on the license.
Windows Update delivers security fixes and feature updates. Check your version and build when troubleshooting and back up important files before a major update or reset. For a used or custom PC, verify the supported CPU, TPM 2.0 and Secure Boot capability. If drive encryption is active, keep the recovery key accessible outside the PC before firmware changes or repairs.