List of the structures:
Torchbearer Node (Beacon of Hope) Node of Torchbearer Master
Grey Guard Node (Obelisk of Balance) Node of Grey Master
Blood Node (Fountain of Blood) Node of Blood Magic Master
Wild Node; Does appear on RMG; Node of Wild Magic Master
Heart of the UG Heart (UG heart); Does appear on RMG; Only in UG
Heart of the Ocean Heart (water heart); Does appear on RMG (only in water)
Heart of the Summit Heart (mountain heart); Does appear on RMG (only on mountains)
Return to nature Income; Conversion Spell for creation specialty
Iron Vein; Does not appear on RMG
Iron Mine Income; Does appear on RMG
Mithril Vein Income; Does appear on RMG
Mithril Mine Income (upgrade of the latter)
Gem Vein Income; Does appear on RMG
Gem Mine; Does appear on RMG (upgrade of the latter)
Gold Vein Income; Does appear on RMG
Gold Mine Income; Does appear on RMG (upgrade of the latter)
Grain Field Income; Does appear on RMG
Grain Farm Income; Does appear on RMG (upgrade of the latter)
Ranch Income (was Great Farm); Does appear on RMG (upgrade of the latter)
Dolmen Income
Druid Circle Income (upgrade of the latter)
Druidhome Income (upgrade of the latter)
Scriptorium Income
Lighthouse Income
Vulcano Income
Igloo Income (Farm variant of the frozen area)
Normal Well Income (normal variant of the corrupted well)
Oasis Income
Monastery Income
Grain Farm (Razed) Razed (razed variant of the farm)
Ranch (Razed) Razed Razed (razed variant of the farm)
Inn (Razed) Razed Razed (razed variant of the farm)
Dark Inn (Razed) Razed Razed (razed variant of the farm)
Labyrinth Explore
Dragon tower Explore
Jungle Temple Explore (only on tropical)
Vulcano Explore (Only in lava lakes)
Pyramids Explore (Only on tropical)
Dark Inn Recruit (for conversion spell of destruction magic)
Centaur Glade Recruit
Halfling House Recruit
Wooden Tower Watchtower (is the new default tower)
Medium watchtower Watchtower (Upgrade of the latter)
Large watchtower Watchtower (was default tower) (Upgrade of the latter)
Orc Hut Unit Spawn (weak spawners, orcs)
Witch Tower Unit Spawn (medium strength spawner, beasts)
Spider Lair Unit Spawn (medium strength spawner, beasts)
Crypt Unit Spawn (strong strength spawner)
Mushroom Field Replenish
Blueberry field Replenish
Colosseum Replenish (grants experience in return for health)
Watermelon Field Replenish
Pumpkin Field Replenish
Dockyard Visit (water only), allows recruitment of ships

Certain buildings can be upgraded into their next level with the upgrade structure spell, which is default from the start. For instance Grain Field into Grain Farm. A new spell allows razing structures (converts them into their razed variant) only in your own domain. These razed structures can be rebuild by using the same upgrade structure spell.

Other changes made to the RMG:
Slight alteration of city clearance.
Removal of water patches in the underground next to lava
Slight change to lava river placement, smoothed
Placement of nearly all structures was implemented in all types of continent creation for the RMG. As a side effect map creation now nearly takes doudble duration for medium maps and even longer for L or XL maps (up to nearly 40 minutes in extreme cases, just let it roll).
Blocking rivers were removed, we did not enjoy these in our games.

In short 4 types or structures can be identified (income: mines, farms, nodes, hearts), (visit: recruitment of units is possible after clearance, such as the dockyard), Replenish (often 1 to 4 in size, need no clearance, often minor bonus such as Watermelon field) and Unit spawners (Orc Hut etcetera).