Perhaps more difficult is the wrong word but different, with lower level classes being more survey classes and upper level being focused on specific topic areas within the major and I’d say most are like that. If you look at the transcripts for many students you see a trend towards improving grades with the upper level classes compared to lower level ones. Students often call those earlier classes “weeding out” classes but that is not the intention. They are simply classes that bombard students with a lot of material and information that is necessary to provide them with a strong background. It is certainly true in many humanities and many sciences.