This question cannot be answered with any precision. It all depends on the instructor and what you will cover in class. As you know both courses can be very broad. In other words, there are too many variables to consider to make any precise predictions at all.
In light of this, it is best to do the following:
First, ask people who have taken both courses and get their opinions. This will be a great place to start. Also you might want to see if there are any rumors about the instructors? Who sounds harder?
Second, you can always ask the teacher for a syllabus and examine the requirements of the course and readings. From this you will be able to gauge the amount of work that is required.
Finally, consider what you like most. If you like a subject, most likely you will excel and study will not be boring.