For a while I have been wondering what is the significance of grey color and green color in my Google Drive. Any idea?
1 Answer
From what I can see, the only automatic thing Google does to folders is add a person icon to folders that have been shared.
You can change the color of a folder yourself, either by right-clicking on it or checking the box and using the "More" menu.
The most likely explanation is that you changed the color of those folder in the dim-and-distant past and it simply slipped your mind.