the difference is that under the statistics you're looking at in the statistics pane are "recieved" statistics -- ie, the amount of queryhits (via hops of ttl) that your client has recieved from other clients. (and that will be emtpy unless you've recently searched for things)

the queryhits you're seeing in the library tab are sent statistics -- ie, the amount of queryhits your client has sent to other clients.

the number under
advanced -> gnutella -> sent -> tcp [query hits]

should be closer to the sum of all the 'hits' in the library. it might not be exactly equal, because the two numbers are counted in different places. (and i don't recall if library hits are incremented on strictly meta-data searches -- i'd be curious to see how the numbers change if they were)