The stats don't break down like that specifically, but "active in some way" includes (I think) anyone who's logged in, loaded a page while logged in, posted, or commented within the last 30 days. The rest of the stats run on "posting an entry", but the "active in some way" judges the level of involvement with some kind of content on the site ... so, in this case, you can see that the difference between "active in some way" and "posted an entry in the last 30 days" is something like 10,000 accounts, which captures the demographic of the people who just read/comment and don't post as much.

(I also think "posted an entry" doesn't include "in communities", so some of that 10k will be people who never post in their own accounts but who are active in communities.)