There are quite a number of differences between a corporation and an LLC. Most smaller companies choose an S-Corp over a C-Corp when considering a corporation. An S-Corp is just a C-Corp in which you have elected S-Corp status. This, like an LLC, simply means that all income to the company has to be dispensed to the shareholders; you can't leave money in the company and declare only capital gains tax, etc.; rather, everything you earn gets taxed to you personally. This is generally called a pass through.
Whether you should go with an S-Corp or an LLC depends a lot on your state as there are some different rules. The IRS is starting to crack down on how people classify wages in an S-Corp, because in an S-Corp you simply have to pay a "fair" salary; that is, a salary commensurate with experience and the market. This opened the door for people to pay themselves a reasonable salary and take the rest as a company distribution, taxed at a much reduced rate. Unfortunately, for consultants, the IRS will classify everything you earn as wages and get you for backtaxes if you ever get audited.
So, the difference between an LLC and an S-Corp for a single person is more about financial strategy than legalese, imo. I'd talk with an advisor before making your decision.
For what it's worth, I have an S-Corp and an LLC. Our LLC is with 3 partners and ~10 employees, and the S-Corp is simply my wife and me. The income that flows from the LLC to me goes through our S-Corp, and it's from the S-Corp that we employ various financial strategies.
Let me know if you have any questions. I've been through this quite a few times.