Service pack:
A collection of patches and updates that have been combined into a single package for ease of installation. This collection of patches and patched components has been tested as a package to offer greater system stability.
A service pack is an update to a software application that provides fixes and enhancements to the product. Service packs can either be downloaded or ordered directly from the company.
Example: The Microsoft Windows 95 Service Pack 1 includes an update, system administration tools, additional components, and drivers for Windows 95.
Windows Update:
Windows Update is the online extension of Windows that helps you to keep your computer up-to-date. Use Windows Update to choose updates for your computer's operating system, software, and hardware. New content is added to the site regularly, so you can always get the most recent updates and fixes to protect your computer and keep it running smoothly.
