Navionics premuim hotmaps help please

I just installed the 898 and got the navionics premuim maps. I was just curious if anyone knows what all the green, red, and assorted color buiys mean. Do the maps have structure marked like the paper maps or am I overlooking it? any help would be appreciated.
Thanks

If your approaching a red buoy, the rule is "Navigate to port (left) when traveling upstream". Green is the opposite. Black buoys indicate a channel junction.