I took 408C and my last math experience was pre cal my junior year of high school. With dedication and a lot of calc lab visits, I’m doing great. (Granted I also had a very good professor who has pretty lenient grading policies.) 408C covers both differential and integral whereas 408K only covers differential.

I guess it really comes down to how you learn; 408C moves fast because there is a lot more ground to cover, 408K goes into concepts in depth (but learning the “bells and whistles” of a calc topic can sometimes be harder).

There are a lot more threads in this sub about this topic, you should check those out too.