Can this folder also be created just from a windows update too?
Yes, it does in case of major updates.
Major updates in Windows 10 such as the November update or the coming Aniversity update change the OS version and not just the build. When these updates are installed the files related to older version of windows will be stored in
windows.old folder. This folder will be automatically be deleted after 30 days.
however the folder date seems to coincide with a windows update
That should be major update that changes the OS version.
Difference between build and version
Consider the following screenshot,
The version is 1511 means it is corresponds to 2015 November release. The updates released after the November update does not add any new features and hence does not change the version of the operating system.
Builds may change with minor updates which contain only bug fixes or minor tweaks.