Silver Enthusiast Visited the site each day for 30 consecutive days 56.9k awarded Bronze Mortarboard Earned at least 200 reputation in a single day 15.4k awarded
It would seem that earning Enthusiast requires almost no effort while Mortarboard is highly non-trivial. This appears to be reflected in the award count (almost 4:1 in favor of enthusiasts).
So, why is the first one silver and the second one bronze?
(A similar question can be asked about Epic vs Fanatic and probably many other).