Yesterday I drove my son to work and, since we arrived early, we sat in the car and chatted. I'm not sure how we got onto the topic, but quite quickly, we began discussing the idea that the things people do are always the best they can do given who they are, what they know, and the circumstances they find themselves in.
Egocentrism has to do with failing to understand that others may be experiencing an object or event differently than you are. Egotism, on the other hand, has to do with failing to appreciate that the needs and interests of others are as important as one's own. Egocentrism is a cognitive domain largely independent of one's personality, while egotism is a personality trait that is largely independent of one's level of cognitive functioning.