The only difference between leaderboards is the time period. Each ranking table takes the scores submitted during a specific time period. A weekly leaderboard only ranks players who submitted their scores for the current week (Sunday to Saturday) while the monthly version ranks from the first day of the month to the last day.
The overall leaderboard lasts for a year, meaning it ranks all the players who ever submitted their scores within the year.
The reason we provide multiple leaderboards with different time periods is to offer players more chances to rank higher.
You may wish to learn how ranking is calculated.
