What exactly is an entrepreneur? Do I consider myself as one?

I know an entrepreneur is someone who organizes and manages a business, but what's the difference between entrepreneur, businessman, and self employed? I'm a 19 year old guy, turning 20 soon and I've been self employed for about 3 months. I do consider it as a 'business', I design websites for my clients, and I'm earning almost equally as a part time job but often higher depending on how well I market my business. I'm writing an eBook at the moment, and it is currently half way done, which I know will be a success. As well as attending college twice a week, and I'm in the process of publishing my first iPhone application which I also believe will be a success. I'm a very optimistic guy, and I truly believe it's not about how good the product or service is, but about how well you can market it. Almost all my money is currently on my savings as I plan to use 80% of all my earnings on investments. I have pretty high standards and a big goal I plan to achieve, now the question is. Should I consider myself as an entrepreneur or just self employed?

Yes, you appear to be a very good candidate toward being an entrepreneur.