Discrepancy between user counts on Leagues versus Users page.
According to https://stackoverflow.com/users, SO currently has ~421k users. (I see 9x4 users on a page, with currently 11,710 pages1, which makes 421,560 users.)
According to http://stackexchange.com/leagues/1/, there's currently 619,716 users.
Where does the difference come from?
1 Note that this number is increasing by the minute. That's why I originally only gave a rounded number.