This is a good article at explaining the difference between PSConfig and PSConfigUI (The gui version) and how to achieve parity between both after applying a patch to a SharePoint server
https://blogs.technet.microsoft.com/stefan_gossner/2015/08/20/why-i-prefer-psconfigui-exe-over-psconfig-exe/
How to run SharePoint PSConfig command correctly
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Redditech 'Ground Zero' Blog 