Greens run a lot hotter and eat batteries. As mentioned they are easier to see. Reason they look great on TV when the cops and military use them is the wattage. Civilians are 5 mw max and LEO and MIL can be up to 40 mw. A 40 in red is even visable during the day.
Greens are also traceable. You can follow the beam back to the shooter. Reds are not unless foggy. smoky etc.