Egoism
Egoism is the theory in which the good of ones act is measured by the happiness and self-interest of the individual own self. For example it may seem ethical for that person if the one taking the action is being benefited and not be bothered by what that action does for anyone else.
What is utilitarianism?
Utilitarianism is the theory in which the good of ones act is measure by maximizing the good for as many people as possible. Therefore the action is good if it leads to happiness for and wrong if it leads to unhappiness to the for a lot of people