Napisao Sluttly, 15.05.2017 at 16:21
Ground special defense are Anti-Air, They are really good against planes like bombers and helicopters
Support units are just the spy planes, which are good at detecting stealth units.
In custom maps and scenarios , this may differ (which is why it's vaguely named), but you can check to see what type of unit it is by going into the units tab at the top right when you have the map/game open.