Which is harder, chemistry of physics? It is generally accepted that physics is harder because of the math.
In fact I am pretty sure that many students opt for chemistry over physics because of the harder math in physics; and life sciences over chemistry for the same reason. Ok, it might be only one of many reasons, and life sciences is an excellent option for interesting material and jobs, but I know that many students are also happy that there is less math in life sciences than physics or chemistry.
In teaching physical chemistry to large classes of life science students, 150 or so, one of the problems is getting to know all the students. Of course there is a large cross section of abilities and interest, and some just cannot get the hang of it. Until the first midterm it is difficult to know who are struggling.