I know that undergraduate programs lead to associate's and bachelor's degrees and that graduate programs lead to master's and doctoral degrees. What are some of the other differences?
 

Answer: There are, of course, many differences. Some of the most important ones are:

1.    Undergraduate programs are more general in nature. They include general education courses in a wide variety of subjects that are not part of graduate education. Graduate programs are highly specialized and much more advanced than undergraduate programs.

2.    Undergraduate classes are usually much larger and less individualized. In graduate programs, students work closely with professors, often on a one-to-one basis.

3.    While some undergraduate programs require a senior project or a similar activity, graduate studies are much more research oriented. Master's and doctoral programs include some class work, but research preparation and defense is a primary focus in most programs. Undergraduate programs usually restrict examinations to those related to individual classes; graduate programs also include comprehensive examinations that are very important.

4.    It is comparatively easy to change undergraduate major subjects and to move to a different school during a program. It is much more difficult to do so in graduate programs, as they are narrowly specialized. Graduate programs in psychology, for example, may be very different from one university to another.

Source: Study in the USA