Microsoft is switching Windows 7 and Windows 8.1 to a cumulative update model similar to the one used by Windows 10. The company is moving away from the individual hotfix approach it has used thus far for those operating systems.
One of the major differences between Windows 7 and 8.1 on the one hand and Windows 10 on the other is what happens when you run Windows Update. Microsoft's two older operating systems usually need to fetch a handful of individual patches each month. If a system hasn't been patched for a few months, this can require dozens of individual fixes to be retrieved. In the case of a clean installation, that number can reach the hundreds.
Windows 10, on the other hand, has perhaps one or two updates released each month. A single cumulative update incorporates not just all of the newest security and reliability fixes, but all the older fixes from previous months, too. If a system isn't updated for a few months or has had its operating system freshly reinstalled, the scenario of having hundreds of individual fixes never occurs. Windows 10 just grabs the latest cumulative update and, with that one package, is more or less up-to-date.
The situation for Windows 7 improved a little back in May. That's when Microsoft announced that a patch rollup containing all the patches released after Service Pack 1 was to be released. This rollup would cover several hundred individual updates, greatly reducing the time taken to get a Windows 7 system up-to-date.
Today's announcement indicates that Microsoft is going to go further down this path.
October 2016's Patch Tuesday will see the release of the first Monthly Rollup for Windows 7 and 8.1. This will be a single package delivering all of the security and reliability improvements released that month. Patch Tuesday will be delivered through Windows Update (WU), Windows Server Update Services (WSUS), and System Center Configuration Manager (SCCM). Subsequent months will have new Monthly Rollups, and these will be cumulative, incorporating the content of all previous Monthly Rollups.