I think all 3 schools (HBS, Wharton, Kellogg) have very different style and focus. I used very much the same essays for all my applications, but I am a very passionate person so i guess none of the school really dislike this quality.
At interview, I "tailor-made" myself to be someone that fits perfectly with their culture (esp if you are interviewing with the adcom). At my Kellogg interview, I focus more on my contribution to community and my involvement at extracurricular at my undergraduate program. At my Wharton interview, I come through as a well-rounded person that knows what my career direction and goals are. Because my goal is to be an entrepernuer, I intentionally discuss a couple of business ideas with my interviewer. At my HBS interview, I make sure I am a very focus and confident person. My answers were very specific to the questions asked. Also I made up my mind on one decision/solution even though it seems like i haven't thought about every aspects of the business. When you use this approach, however, you have to provide very strong supporting on why you pick this decision/solution. Basically, you have to sound very analytical and confident.
In short, you have to slightly modified your style to make you "fit in" to the school culture. This is what "REAL MARKETING" is all about. It's about positioning the product (applicant) to fill consumer (adcom) needs. | 
