More than that: they're different vatiables. One is actual, measured time and distance: this is how drivers are paid. The other is estimated time and distance w

More than that: they're different vatiables. One is actual, measured time and distance: this is how drivers are paid. The other is estimated time and distance wrapped up in a risk modeling / worst-case analysis: this is how riders are charged. Estimation vs. measurement. The two converge in an ideal world where risk drops to zero and estimation methodologies are perfect.