I've worked at places where it turned out different parts of the organization had a different idea of what a "user" of the core product was.

The team using Salesforce, the data warehouse team, the application development teams, all with different mental models of what "we added 5,000 users today" actually meant in concrete terms.

Oh man. This gets really exciting when in addition the Finance team has to tell the SEC how many active users there are, but they're using different definitions every quarter because they get their numbers in some non-reproducible way from whichever of those other teams has time to help them this month.

Source: my own years on data warehouse and application development teams.