The nature is that 120B is just more difficult than 120A. During the time I took 120B with Fuchser, he was a quiet lecturer and mumbled a bit but was clearly passionate about the work he was presenting. Thankfully lectures were recorded and discussion sections were not mandatory. He received criticism about the exams being difficult but honestly it wasn't that bad (although be aware that I took interest in this content, despite how nuanced it could be at times, so my interest probably helped me study and engage with the content more). He also let us use one notecard as a cheat sheet for the final. The assignments were easy, it was just a one-page "reaction paper" of what we learned that week; it was very open-ended and graded pretty much on completion. There was also a final project where you read an article and make a presentation on it. I had a lot of fun with it because I found the article interesting. Going to his office hours was also nice because he's very approachable and enjoyed explaining the concepts in depth. Overall, if given the chance, I would say to take this class with Fuchser.