Windows Update clients normally download updates over an Internet connection, although Microsoft makes provision for installing updates on computers without an Internet connection and a range of alternative methods and programs also exist to install updates. Security updates or critical updates protect against vulnerabilities to malware and security exploits.
Administrators should read the release notes a given update comes with to determine its impact and applicability.
In order to switch from Windows Update to Microsoft Update, you can visit this Microsoft site which works for all versions of Windows.
Another way to do it would be to launch Windows Update like you normally do and then click the appropriate link as indicated below.
When you are using an Office 365 installation of Office 2013 or Office 2016, then the updates will not be offered via Windows Update but will be installed automatically.
You can manually check for updates from within any Office application.