From the Copyright Office:
How is a copyright different from a patent or a trademark?
Copyright protects original works of authorship, while a patent protects inventions or discoveries. Ideas and discoveries are not protected by the copyright law, although the way in which they are expressed may be. A trademark protects words, phrases, symbols, or designs identifying the source of the goods or services of one party and distinguishing them from those of others.
I think you will find that reading over the FAQ sections for both the Copyright Office and the Trademark Office will be helpful:
U.S. Copyright Office - Frequently Asked Questions Questions and Answers - USPTO- USPTO (select Trademark in the top menu)
copywriting vs trademarking 
