Question

Which has more total thermal energy: a glass of water or a pool?

Answer 1

The pool. The pool is a larger object which means it will obtain more thermal energy then the glass cup of water.

Answer 2

There is a difference between energy and temperature. You can have a swimming pool and a beaker of water at exactly the same temperature. Even though they are at the same temperature the swimming pool represents a much bigger thermal energy store than the beaker of water.