folder properties

when you go into file explorer right click on a folder and go to properties under the general tab there is a heading "attributes" next to this you have a tick box for read only. what is the difference between this and going to the tab security and having read only options in here?

When I right click in file explorer and invoke properties I get the size of the first subfolder, but not subsequent subfolders. As you can see from the image linked, drive D: has a folder Usenet with a subfolder Newsbin. Newsbin has 2 subfolders, Downloads and Downloads - NZB. Downloads is...