Oops! Then I am confused!
What is the exact difference between “Latest Activity” and “What's New”?
good question?
Most people will use Latest Activity
Latest Activity is a submenu of Whats New
Click on whats new and then click on latest activity and you'll see the diference
TBH just use what you are used to using and there won't ever be confusion.
For me I always use new posts. I see all of the new posts but read the ones in which I am interested. Once done I "mark forums read"so that the next time I go to new posts I see just that and none of the others that were there the last time I looked