most of them I understand multiple and gold but that's it level, magnet and rank not too sure. Emerald and sapphire I don't see a difference them the last one No idea what so ever
Rank gives a multiplier to the amount of gold you receive from your tower based on it's level. Level tower multiplies the amount of exp you receive for each block that falls that increases the Rank bar. Magnet is a currency used to purchase upgrades and the Magnet Tower multiplies the amount you receive when they're unlocked. Similarly Sapphire and Emerald have their own prestige upgrades that you sink that currency in to.