The most common path can be different from the Happy Path. It shows how the process most frequently performs (how it happens most of the time when the process is executed). It is somehow the business process “as is” and is shown by the Process Mining solution (with the process data) with the biggest percentage of use.
Having a different Happy Path and Most Common Path is really interesting to show off to the business as it could highlight real troubles. So going deeper here may be the best first analysis to do !