The blue ones are ones with no new posts .
The ones with the red star are topics that you have made a post on .
The scrolling ones..nobody knows for sure
..I think they mean "hot topics"You will also notice the little red square next to some of the circles .
If you click that , you will go directly to the first unread post .
Also , the green smiley ones (
) are ones that have been moved to the proper section.And the light bulb ones are stickies that won't/can't move.