The black/yellow buoys are used to mark dangerous Areas, like Wrecks or sands.
Green and red are for the shipping Lanes, red/white (vertical) mark the middle of a shipping Lane.
From Sea coming, the green buoys are on Starbord side.
Here an Example:
Sorry for the many Pictures, but i would bite in my Mouse if they where of the wrong Side ingame.
The Lights are reglemented too, but i think its too much work. But you can count the Flashes (at Pic 1) and see, where you must pass the Buoy.
But it is a great Advancement in my Opinion. Nice to see that.