Quick glance I see 4 types:
Light blue
Light blue bold
Dark blue
Dark blue bold
I don't know why there is to many? I think most forums have two: bold for threads with new posts, and not bold for threads without new posts since your last visit. This makes it very quick and easy to see what threads I would like to visit. This current way I have no idea what is new since the last time I visited.
In the images below - in one I can clearly see what is new. In the AMASS I could not even tell you what's what.

