Both Estragon and Vladimir are essentially Everymen, representing all of humanity, but they also contrast in some ways. Estragon is primarily concerned with feelings, particularly his own suffering, rather than intellectual thoughts, and he has trouble understanding much of Vladimir's logic and philosophy. He displays intuitive leaps, however, that go deeper than Vladimir does with his logic. If the two primary characters represent two parts of a person, Estragon is the body. The beatings Estragon says he receives represent the suffering that afflicts and traps humanity. There is nothing noble about this suffering—Estragon's complaints about it are self-pitying, and the fear of another beating keeps him locked in the endless waiting.
Vladimir is the more logical and intellectual of the two primary characters. He is the only character who remembers most events from one day to another, and he works the hardest to fit those events into a logical time frame, despite conflicting evidence. He tries to explore philosophical ideas logically, but often misses deeper truths Estragon seems to grasp instinctively. If Estragon represents the body, Vladimir represents the mind, with all its ability to deceive itself.
In contrast to the other characters, Pozzo is a wealthy landowner with power and resources. He clearly sees Vladimir and Estragon as beneath him but condescends to talk with them anyway. His concern with appearances and social conventions is ridiculous, pointing out their meaninglessness. Pozzo uses his power over Lucky to abuse him horribly. But his power and resources are ultimately useless—they don't give his life meaning or protect him from misfortune. When he becomes blind, he must rely on his slave, Lucky (who was previously merely a convenience and for entertainment) to help him navigate life, becoming pitiful in a single stroke of fate.
As Pozzo's slave, he must constantly carry burdens that are not his own. His body is constrained, much like his free will. This might be why he seems not even to consider leaving when Pozzo becomes blind, losing most of the power he had wielded over Lucky. However, Lucky demonstrates some willpower during his long speech in Act 1, and he is upset by the prospect of Pozzo selling him, which suggests he may choose to remain in his role. There is a dependency between Lucky and Pozzo that seems related to, but not limited to, their inequality.