Final answer:
Psychological egoism claims humans are always motivated by self-interest, while ethical egoism is the belief that pursuing one's own self-interest is morally right.
Step-by-step explanation:
Psychological egoism is the view that humans are always motivated by self-interest, even in what seem to be acts of altruism. It claims that people choose to help others ultimately because of the personal benefits they expect to obtain from doing so. On the other hand, ethical egoism is the view that it is morally right to pursue one's own self-interest as a guiding principle for behavior. While psychological egoism describes how people actually behave, ethical egoism provides a normative claim about how people should behave.