How to identify build number of a macOS installer?
The most reliable way of telling the build number is to check the SystemVersion.plist file inside the installer's OS image file (and not the build number of the installer app itself).


Mount /Applications/Install macOS Sierra.app/Contents/SharedSupport/InstallESD.dmg
Mount /Volumes/OS X Install ESD/BaseSystem.dmg (hidden file)
Open /Volumes/OS X Base System/System/Library/CoreServices/SystemVersion.plist and examine the build number under &lt;key&gt;ProductBuildVersion&lt;/key&gt;