There are schools that require an applicant to submit a Statement of Purpose instead of a PS, the thrust of which is to present an applicant's goals in terms of what major to pursue, what research direction to take, and other specific study and career plans, if any. Therefore, in this case, you are required to submit a similar essay but with greater emphasis on your specific study and career plans. Most applicants are confused with the difference between a PS and a Statement of Purpose. This is not to say, however, that a PS cannot be a Statement of Purpose and vice versa, because as you will discover in the next section, these two can actually overlap depending on the outline you have created.
Often, the first draft is not the essay you originally envisioned. You might even discover that your ideas about your theme have changed as you have been writing. If you do not like the way certain sections are stated, re_arrange them. Once you are pleased with the body, make sure the conclusion and introduction still match it and complement the way you see your topic at this point. If not, rewrite them to fit the essay you did write and the way you see your topic now.