There were many differences between the study and how a real prison system works. "Ethical, legal, and practical considerations set limits upon the degree to which this situation could approach the conditions existing in actual prisons and penitentiaries." (Zimbardo). This meant that there were rules that participants had to follow in order to have a safe and ethical environment to conduct the experiment. There were only a small sample of participants who agreed to go to take part of the study compared to the vast amount of inmates throughout the country that regularly do not choose to go to prison. The participants were all white college males with the exception of one person who was from oriental descent. This does not provide an accurate sample relative to prison population. The maximum sentence for the participants was only two weeks and their sentence could not be extended. "Unlike other prison system, prisoners could not be extended indefinitely for infractions of the internal operating system." (Zimbardo). There were many aspects of prison life that inmates and guards have to deal with. These aspects could not be implemented in the experiment because they would not be considered ethical. "There was no involuntary homosexuality, no racism, no physical beatings, no threat to life by prisoners against each other or other guards." (Zimbardo). This experiment could not be compared to real prisons because of the unlimited amount of variables that can't be replicated in an ethical psychological experiment. (Zimbardo)

The experiment does not prove correlation or causation of environmental factors that cause inmate and guard interactions, but does provide information that can be attributed to a couple of theories. The experiment can teach us about the power of authority, conformity, social learning theories, obedience, and ethics. It gives insight as to how an environment can influence, alter, or enhance our behaviors, and how behaviors can effect our psychological responses to situations. "In one sense, the profound psychological effects we observed under the relatively minimal prison-like conditions which existed in our mock prison make the results even more significant and force us o wonder about the devastating impact of chronic incarceration in real prisons." (Zimbardo).
References:
Banks, Curtis. Haney, Craig. Zimbardo, Philip. "International Journal of Criminology and Penology." Intropersonal Dynamics in Simulated Prison. (1973) 69-97. Web. 17 Oct. 2016