Pack for Windows 95. The task manager in Windows NT is much better than that in Windows 95. Not only can you shut down an application, but you can also change your logon password, end network connections, end separate threads and monitor various resources. Most of them have been intelligently integrated into the desktop and Explorer. An examples of this is DOS-based utility programs like PC Tools.
Service packs are mostly a slew of system component updates to help eliminate bugs.
Between service packs when important issues heat up, Microsoft issues hot fixes. Hot fixes only contain bug fixes for very specific issues. As a general rule, it is recommended that you install each new service pack and all hot fixes.