There are two types of servers: Mining Servers and Battle Servers. 
On the Mining Servers, as compared with the Battle ones, there are:
- more Pits and Mines
 - more Ruins (up to 7) in the Kingdom
 - much more Ruins for Empire
 - less % of Monsters Army that march out from Ruins for attacks, and the Monsters begin attacking earlier not waiting till they multiply a lot
 - ranks are affected by bigger coefficient of the Army Strength Rating
 - bigger spread in the scale of ranks
 - more strict Ranks Rule – players cannot attack other players of ranks lower than own
 - squares for new players with 4 free villages
 - less squares unfitting to new city foundation
 - the Ancients’ Protection (received as quest reward) that’s staying in the Capital for 2 months
 - more Gods Favour points to accumulate in Temple
 - increased capacity of the Cache
 - less squares of high level
 - more native terrains
 - more the "Exchequer" science gives
 
On all servers where you continuously prolong Subscription:
• The Black Gems that you obtain in the Game can be withdrawn from server and transferred to another server or exchanged for real money