EECS 183 vs. EECS 280 vs. EECS 281

I just want to know, I am currently taking EECS183 and I am struggling a bit on the exam (got a score in the low 70s, is that good? Not sure if the exams have a scale) and completing the 2nd project. How much harder is EECS 280 and EECS 281? I need to know this because I may or may not major in CS.

http://www.eecs.umich.edu/eecs/undergraduate/survey/all_survey.2014.htm

Based on your previous posts about CS, it doesn’t seem like you should major in CS… 281 is substantially harder than 183

Thanks guys.