Historic
HISTORIC is usually used to describe something that is so important that it is likely to be remembered:
1) very important in history 역사적으로 중대한, 유명한
* a historic voyage 역사적인 항해
* a historic decision 역사적인 결정

2) having a long history 긴 역사를 가지고 있는
* a historic building 역사가 오래된 빌딩
 
ex) Today is a historic occasion for our country.

Historical
HISTORICAL usually describes something that is connected with the past or with the study of history, or something that really happened in the past

1)about or based upon people or events 역사에 바탕을 둔, 역사에 관련된
 * a historical document 역사 서류
 * historical novel 역사관련 소설

ex) I have been doing some historical research.