See how a running total differs from a rate of change with parcel deliveries:...

https://record-wiki.win/index.php/When_Should_I_Use_a_Step_Graph_Instead_of_a_Line_Graph%3F

See how a running total differs from a rate of change with parcel deliveries: 120 parcels by noon is a total, while 30 parcels per hour is a pace over a time window. Clear units help you read the chart and explain what changed.