A running total tells how many parcels have arrived so far, while a rate tells...

https://activecalculus.org/author/Running-Totals-Rates-of-Change

A running total tells how many parcels have arrived so far, while a rate tells how fast they arrive. Compare 120 parcels by noon with 15 parcels per hour, and see why the units and time window matter when reading a work chart at a glance.