A project manager is managing two agile teams and reviewing their metrics to find out...

The project manager should not compare the velocity of two agile teams as teams can size items differently. Velocity is a measure of the amount of work a team can complete in a given time period. It is not a measure of the quality or value of the work. Comparing the velocity of two teams can lead to inaccurate conclusions and unhealthy competition. Instead, the project manager should use the velocity of each team to help them plan and forecast their own work, and focus on other metrics that reflect the outcomes and benefits of the project. References: Agile Practice Guide, page 48; PMBOK Guide 7th Edition, page 97.