selfish

I've known of people who always wanted more money (and everything else), but were willing to spend money freely - if only to impress or buy their friends. Such people are greedy, but not stingy. I have also known of people who did not have much money and were not obsessed with getting it, but were unwilling to spend it. They were stingy, but not greedy. To be sure, there are plenty of people that are greedy and stingy at the same time. I would be more inclined to call the kid in the example stingy. If he was also demanding more toys and candy, he could also be called greedy.

The kid's attitude here is better described as stingy or selfish. 'Stingy' is when one doesn't want to share what they have ( be it money or any other thing) with others. A person who loves to gather lots of money and always wants more of it and at the same time doesn't want to share it with any one is both greedy and stingy.

I second Eliot's answer. Stingy and greedy are not the best choices because the child is sharing, not giving or buying. Also, if you want to get specific, stingy and greedy don't exactly describe a person who loves money. You can love money in many ways. Stingy means unwillingly to spend and greedy is wanting a lot of something. So a stingy person may love to hold on to their money (but not necessarily) and a greedy person would love to have more money than what they already have.

You would use greedy for that child your talking about. and in terms of money greedy and stingy are opposites I think. You would call someone who is stubborn stingy. If you said someone was stingy about money it would mean they use it carefully it doesn't mean they're greedy or want more.