How we cite our quotes:
"I’ll take ham and eggs," the man called Al said. He wore a derby hat and a black overcoat buttoned across the chest. His face was small and white and he had tight lips. He wore a silk muffler and gloves. (20)
This is the portrait that Hemingway paints of criminality; there’s a sort of cliché to the black overcoat and derby hat.
"Give me bacon and eggs," said the other man. He was about the same size as Al. Their faces were different, but they were dressed like twins. Both wore overcoats too tight for them. They sat leaning forward, their elbows on the counter. (21)
The men are made identical by their criminal status. Because criminals are defined simply by what they do, there is little difference between criminal A and criminal B.
"Just a bright boy," Max said. He leaned forward and took the ham and eggs. Both men ate with their gloves on. George watched them eat. (46)
Before we know for sure that Max and Al are killers, we get little hints. Here, for example, they eat with their gloves on (presumably to avoid leaving fingerprints at the scene of the crime).