Egoism is usually a philosophical idea: acting from self-interest, or believing that moral behaviour should serve one's own interest. Egotism is more everyday: it means talking about yourself excessively, or believing you are superior to others. A useful hook is that egoTism has a T for Talking about yourself.
The core difference
Egoism is a philosophy or tendency of self-interest; egotism is boastful self-focus in behaviour.
- egoism — the tendency to think selfishly, or the belief that moral behaviour should serve one's own interest: Ethical egoism holds that people ought to act in their own self-interest.
- egotism — talking excessively about oneself, or believing oneself superior to others: His egotism showed every time the conversation turned back to his own achievements.
How to tell them apart
Both words come from the Latin ego, "I", so their overlap is not surprising, and each word can even stand in for the other in some dictionary senses. But in everyday use, egoism tends to describe a belief system or a general self-interested tendency, often discussed in philosophy and ethics. Egotism tends to describe a personality trait, the habit of boasting or making everything about oneself.
The mix-up shows up in essays about ethics, where writers reach for "egotism" when they mean the philosophical position of "egoism", or vice versa. If the sentence is about a moral theory, egoism is the safer choice; if it is about someone's boastful behaviour, egotism fits better.
