The older waiter says to the younger, "we are of two different kinds," this establishes the most obvious conflict. The younger waiter is more selfish, 'in a hurry,' and the older waiter is more selfless: inclined to stay at the cafe in case someone (like the old man) needs it.
The old man needs the light in the cafe and the old waiter needs the daylight before he can sleep. 2) The younger waiter doesn't need to stay, he seemingly has everything: a waiting wife, a job, and he even says that an hour means more to him than it does to the old man. This seems logical given that the old man recently tried to kill himself, but it is not. The younger waiter has no way of knowing how much that hour at the cafe means to the old man. But the older waiter does know how much it means.