The RUN signal allows the Pi SoC to be reset,
the EN allows the PMIC to powered up and down.
the EN pin connected to 5V via a 100K 63mW resistor, RUN to 3V3 via 10K 63mW.
Update : From a Raspberry Pi engineer, the answers to the questions are as follows:
Momentarily short GLOBAL_EN to ground to restart a halted RBP4.
Momentarily short GLOBAL_EN to ground to restart a running RBP4. Usual caveats about suddenly powering off your system apply.
and something that made me laugh. . . .