This article distinguishes between the two transaction metrics found in the ProTop Trends Advanced Dashboard.
The ProTop Trends > Advanced Dashboard > Connections > Transactions metric as seen here:
... is the rate of transaction commits per second during the sample interval.
The data comes from the VST field _actsummary._summary-commits, which is seen as “Commits” in promon R&D, 2, 1.
The ProTop Trends > Advanced Dashboard > Transactions > Transactions metric as seen here:
... is calculated by ProTop and is the count of the users who have an active transaction during the measured interval.