Examine the course descriptions found in your university's academic course catalog. Most universities offer these online as a downloadable PDF file. In most academic catalogs, the course descriptions can be found at the end in the last pages of the book. Each course description will give you a paragraph summary of the course, indicating to you the scope of the material covered throughout the course of the semester. This should give you some idea as to whether or not the content will work for your degree program and fit your vocational goals. The course number should tell you something regarding its difficulty. Typically 100 or 1000 level courses are freshman level, whereas 400 or 4000 level courses are upper-division and more difficult.
Research the professors offering the courses. You can learn much about a course by learning about the professor who offers it. Most professors are scholars who have published one or more scholarly works. Read an excerpt from one of their books or read an article that they have published to try to determine their scholarly biases and what they consider important in their field. You can set up an appointment or call the professor to ask them about the course. Repeat the process for the instructor of the second course you are comparing.
Read online reviews of professors and their courses by other students. This is one of the best ways to learn about the "nuts and bolts" of a course. Websites like MyEdu will provide you with free information about a professor's course based on what other students have written. Students will typically provide an overview of the pros and the cons of the course. Students who have already taken the course generally discuss the types of exams, paper assignments and professor accessibility.