Alrighty, so, you know how young children often believe that a taller container will have a greater volume than a shorter container? Even after seeing that both containers hold the same amount, some children will still think the taller container holds more. It may take measuring the water a few times before they get it.
<em>If it overflows, the first container is bigger, or is able to hold more water. If all of the water from the first container can be poured into the second container without completely filling it, then the second container holds more water.</em>
The tallest container holds the most liquid. Identical containers can have a different capacity.