I know you aren't supposed to compare your kids, but sometimes the differences between our two amaze me. This is one of those things...
We were eating breakfast and Aurora finished her breakfast and got some fruit. Quinn, who had 3-4 more bites of his food left, pushed his bowl away and said, "Ah dum!" (all done). He was ready for fruit, too!
I explained to him that when he had finished his food, then he could have fruit. I showed him Aurora's bowl and his bowl and restated that he needed to finish his food before he got fruit. He was very angry about this and cried for 5 or so minutes. Then, after I once again told him he could have fruit after finishing his food, he grabbed his bowl and gobbled down his breakfast. He was quite happy when he got his fruit.
Aurora at this age wouldn't have even understood that explanation or maybe just not cared about it. She would have thrown a fit and carried on and on until the table were cleared. She wouldn't have finished her breakfast and wouldn't have gotten fruit. We actually have been fairly careful not to set up situations like that for her even now because she still doesn't always grasp the concept or feels the need to fight it to her detriment.
But Quinn... he gets it most of the time. He seems to understand that if he does or doesn't do something, something else does or doesn't happen. He will generally protest for a while and then cooperate. Usually these things are very small, immediate consequences, like eating breakfast and then getting fruit or picking up toys and then getting new toys, but he amazes me with his understanding.
It's so interesting how different kids' brains work! I love watching their personalities emerge! :)