Purpose

• Business writing tends to be impersonal. The individual who engages in business writing is composing the words with his company or organization in mind, along with its potential customers and supporters. Business writing usually has a specific goal, such as introducing a new product or announcing an event. While personal writing can indeed have a purpose, such as inviting a friend to a wedding or thanking someone for a gift, achieving a goal is not the central focus.
  
  

Style

• Business writing tends to be fact-based, concise and clear. Keep sentences short and uncomplicated so they can be easily digested by readers. Avoid flowery language or confusing structure. Personal writing can take this form, depending on the person doing the writing, but personal blogs and emails will usually take on a free-flowing, conversational feel. The style of personal writing has a wide range and may include abbreviations, such as "OMG he is so cute!" or drawn-out descriptions.
  
  

Formality Versus Familiarity

• Business writing has a formal approach that most personal writing lacks. A business letter will often include the recipient's address at the top of the page, will address the recipient by her formal title and will end with a cordial closing. Personal letters are more likely to incorporate an individual's nickname or end with a casual closing such as "Cheers!" or "Miss you." Personal writing demonstrates a sense of familiarity in the place of formality.
  
  

Grammar

• Flawless grammar, spelling and punctuation are essential to good business writing. A misspelled word or misplaced apostrophe can make a business appear sloppy and put its credibility on the line. Depending on the degree of formality, business writing may even cut out contractions, opting to type out "do not" instead of "don't." No such restrictions exist for personal writing. This writing is a reflection on the individual alone, so it is up to his sole jurisdiction.