début vs introduction

début

• A person’s or thing’s first appearance before society or another audience; one’s “maiden voyage”. 

• To make one's début. 

introduction

• The act or process of introducing. 

• A written or oral explanation of what constitutes the basis of an issue. 

• A means, such as a personal letter, of presenting one person to another. 

• An initial section of a book or article, which introduces the subject material.