The differences between level 1 and level 2 nodes are just not clear for me. A level 1 node requires double the amount of deposit and there will only be 512 level 1 nodes as opposed to 1024 level 2 ones. But are there any other differences e.g. in functionality? What can a level 1 node do that a level 2 node can't? And similarly, how would a level 2 node differ from a level 3 node?