Historic - historical
From Hull AWE
- Historical means 'belonging to history or to the study of history'. So a historical survey of a problem is a survey which considers the history of the problem, and an historical novel is a novel which describes, or is based on, historical events, i.e., events which actually happened.
- Historic means 'significant, famous, or important in history'. So "That was an historic day for the country" means "That was a significant or important day in the history of the country".
For a note on the difference between "a historic" or "an historic", see H with indefinite article.