How are copyright and trademark law different?
Answer
Trademark law is intended to prevent consumer confusion around the source of a good or service, as indicated by a "trademark". A trademark is infringed when someone uses it in a way that confuses consumers about whether the good or service is from or sponsored by the trademark holder. Simply using the trademark to refer to that company or brand -- in scholarship or as a parody, for instance -- is typically protected as a trademark fair use. (While this is the same term as "fair use" in copyright law, they are two separate doctrines.) Trademarks last as long as they are in use, and almost anything can be a trademark -- a color (as in Tiffany blue), a sound or jingle, and most commonly, a slogan or logo.
Copyright law is intended to provide rights to creators of books, music, films, art, software, and other copyrightable works, in order to help those creators and thus incentivize them to make more creative works. A copyright is infringed when someone makes one of a specific set of uses of copyrighted works -- copying the work, distributing copies, publicly displaying or performing the work, or making "derivative works" (translations, adaptations, etc.) -- without authorization or another legal right. Other uses of the copyrighted work (such as a "private" performance) are not copyright infringements. Copyright law also has numerous protections for using works, such as rights of teachers to show movies or works of art in their classroom, rights of performers to make covers of published songs, and "fair use", which covers quotes, parodies, search engines, and many other uses. Copyrights last until 70 years after the creator's death, or, for corporate works, 95 years from publication or 120 years from creation. Copyrights can attach to eight different types of "copyrightable" works -- literary works (stories, poems, software), dramatic works (plays), audiovisual works (movies), musical works (scores), choreographic works (mime and dance), architectural works, and sound recordings.