Individualism means to stress independence from group standards, as well as self reliance. It stresses individual achievement over collective achievement. Egoism refers to an overly developed sense of one's self-importance. Individualism is more rational, recognizing that collective action might be necessary, so long as participation is voluntary. It recognizes the importance of others. An Egoist would probably not recognize the importance or contributions of others. At least, that is how I interpret it.