Sigmund Freud opined that human behavior can be understood by studying the past experiences of a person -- especially the childhood -- and how the person perceived these circumstances at various developmental stages of his life. This is also known as psychoanalytic theory of personality.
On the other hand, Carl R. Rogers stated that human behavior can be understood exclusively by studying how the person perceives himself internally. This is known as humanistic personality theory.
Freud's theory says that if it was socially acceptable, people would basically lead selfish, violent and incestuous lives. They would completely and blindly pursue pleasure and attain it at any cost. This is because according to Freud, human nature is basically driven by sexual instincts.
Rogers' theory, while agreeing that human nature has a tendency toward aggressiveness and violence, says that human nature is driven by the inherent desire for positive self-actualization, such as positive reinforcement and appreciation from society.
Freud's theory maintains that humans are driven by their unconscious minds, and therefore they are basically irrational and alogical. This theory says that human behavior is the result of unconscious instincts that are uncontrollable; their manifestation results in day-to-day behavior of a human being. The behavior is controlled by the norms of the society.
Rogers' theory says that human behavior is controlled by rationality and reason. The behavior is controlled by the need for actualization; when it is stopped by psychosocial conditions, it converts into destructive and antisocial behavior.
Freud's theory says that humans are driven by the unconscious mind, where thoughts, memories and ideas are hidden from someone's immediate attention. People do not realize that they have these drives; instead, it is manifested through personalities. This is, according to Freud, the root of all behavior, feelings, reactions and perceptions. The unconscious moves beyond cognitive awareness and is the basis of all personality traits.
Rogers' theory says that the unconscious mind is not part of the personality, let alone the basis. Rather, it is only a part of the process. The unconscious, according to Rogers, is what the mind construes as perception, and not the main driver of human behavior.