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Iron Golems are the Friendly Giants that protect villagers, although the player can build their own army with 4 blocks and a pumpkin.
Any naturally spawned Iron Golem will still generate with vines, however, Player Created Iron Golems will be clean and made purely out of Iron.
To make it more clear that there are different. Naturally Spawned Iron Golems DO NOT drop iron ingots, only Player Created ones do.
To make the world feel more alive, some mobs will automatically be given a name upon first spawning, this includes villagers and cats.
Iron Golems also get their names assigned to them aswell... "we like to believe its the villagers giving them their special name after building one" or its a text file found at data//oaksrework//texts//names//iron_golem.txt this allows you to create your own datapacks (or mod support) to add more custom names.
Non Player Created Iron Golems also do not drop iron at all and only Iron Golems that are player create drop Iron Ingots.