Biochemistry is a rigorous field of study involving foundational and introductory courses in biology and chemistry with laboratory components, as well as advanced courses exploring topics such as cell biology, microbiology and genetics. Biochemistry majors also take mathematics and physics courses.
Biochemistry is a multidisciplinary field, where Biology (the analysis of components of the cell) and Chemistry (the interaction between elements) are combined, in order to understand the processes taking place in living organisms and ways to optimise them as much as possible.
Mathematics is not essential for many biochemistry courses but a lot of biochemistry revolves around interpreting statistical data and calculating concentrations, kinetics and constants. Studying maths will support the study of key biochemistry disciplines.
Biochemistry is harder than biology as it deals with the chemistry of life rather than living organisms. For most people, that's more complex and difficult to understand.