The reflection coefficient is the ratio of reflected wave to incident wave at point of reflection. This value varies from -1 (for short load) to +1 (for open load), and becomes 0 for matched impedance load.
where ZS is the impedance toward the source,
ZL is the impedance toward the load.
This is the ratio of maximum voltage to minimum voltage in standing wave pattern.
It varies from 1 to (plus) infinity.