Hedonism and utilitarianism are similar in their evaluation of the goal of moral behaviour as some version of pleasure or happiness and the minimization of its opposite. They can both view pleasure or happiness as simple and immediate, or complex and matured. Where they differ is the scope of evaluation which justifies the behaviour as moral. Hedonism tends to be individualistic while utilitarianism tends to be social. A utilitarian must evaluate the happiness result for the total consequence of an action, which typically effects many people. A hedonist could very well throw consequences to the wind if the action feels good to him or herself. In a sense, you might consider utilitarianism to be model for social hedonism.
