The document discusses the differences between formal and informal letters. It provides guidelines for the layout of both types of letters, including addressing, date format, greetings, body paragraphs, and closings. For informal letters, greetings include "Dear John" or "Dear Jane" while formal letters use "Dear Mr. Smith" or "Dear Madam." Closings like "Love" or "Best wishes" are informal, and "Yours sincerely" or "Yours faithfully" are formal. The document also gives examples of phrases to use in the letter body for different levels of formality.