The Delta fixlets only become relevant if your endpoint is at the build version from the prior month’s Patch Tuesday update. If the endpoint is at any other build version, the corresponding Cumulative will be relevant. The build version is listed in the KB article for each Cumulative/Delta update.
There is also a feature to turn off the Delta fixlets and only make the Cumulatives relevant. This can be achieved with the following client setting:
_BESClient_WindowsOS_ApplyCumulativeUpdateOnly = 1