How difficult are graduate level chemistry courses compared to undergraduate

Juche

I have talked to people on this subject and I get different responses. Some say the graduate level courses are not much harder than senior level undergraduate, some say they are 5x harder. My brother for example is doing math graduate courses and says they are not any harder than undergraduate (I have had other sources in other majors like microbiology say the same thing to me). Does it just depend on the undergraduate and graduate universities you enter?