Gods are, well, Gods. they do not usually walk around in their true form on the natural world - it can screw things up and they have rules about that. Most often if you 'see' a God, you're looking at a projection or an avatar - a mortal body the God is riding around in to visit the mortal world. Demigods are those beings who have *some* connection with the gods but often are not as powerful - like low ranking gods. Powers are more plentiful than either one and roam around freely with no obligation to the God-lands or laws there of.