kaplan complete text?

The complete text is “complete” i.e. contains information on all areas of the syllabus. The essential text is usually cut short. It just has basic principles and those areas that Kaplan thinks are examinable. Usually the essential text isn’t worth it as many important aspects and understanding (e.g. advantages and disadvantages are cut). Try to get another book if you have the essential text and you’re studying for the subject for the first time. However, the essential text does have practice questions and answers at the back so it’s worth it in that sense.