A biography tells the story of a person's character, life, and achievements. A biographical sketch is shorter and much more specific. We may define a biographical sketch as the description of a person, his physical appearance, work, temperament, habits, achievements and other salient personal traits.
A bio- sketch is always written by someone else except the person on whom it is written. It includes a person’s age, education, profession, disposition and attributes. It presents the facts about a person’s life and provides an overview of the life of a person. It tells us about his interests, influences in his life and his accomplishments. It is usually written in the third person.
The sketch should provide readers with basic information about the person, and give them a sense of the person's character. You must use specific details and engaging language to demonstrate what makes the person you're writing about different from anyone else.