The one that shows on the main forum is cached; as in it won't always update on every reload. The other (full page) is not cached, and will always display things "live". That's the info I have received from support. Same goes for the birthdays at the bottom of the page. Very annoying if you ask me, but apparently they can't solve this...
You have your birthday already since several days

At least, on my PC it still shows.
Wurde die Lesebestätigung bei den PM's vergessen oder bewußt nicht mehr "eingebaut"?

I didn't notice that yet since I haven't sent any PM since the new software. I'll look into the matter. But can't seem to find that option at the moment.