RHEL 6 vs. 7 settings

I was asked a question regarding settings by one of my customers planning an upgrade of their systems from RHEL6.9 to v7.5 or 7.6. They will not be undertaking a Vertica upgrade at the same time and are running v9.2.1. The questions raised during a call was if there were any differences in the settings required for the upgrade? Specifically RH settings were asked about but if there are any Vertica settings that should be different then that would be of interest too!