Comparing the formulas (not values) in two cells

I'm teaching basic Excel skills to students in school and need to improve the level of correction of the student results. I know how to compare the value of two cells using formulars and how to use conditional formatting based on values of the cells. But I need to manually check, if my students used the correct formulars in the cells.

Is there a way to compare the formular in two cells or to highlight cell with conditional formatting with formula not based on value but on the formular in the cell?

e.g. for the cell B1 formular should be =sum(A$1:A4)

student uses =sum(A1:A4)

=> highlight cell by conditional formatting red

or => Text "False" in Cell C1 by comparing B1 and the cell with the correct formular (e.g. D1) via some kind of formular

I'm lost.

Many thanks