Excel macro - color comparison 2 doc

Hi all experts via Excel

Please can someone advise me how to create a macro to the next case?

I have 2 documents. The documents are numbers (prices). If user push the button in 2 doc (macro), function will compares a cells and when it finds a difference function will colour this cells. Position of the cells are not changed.

Document 1 does not change.
Document 2 is open to change, there is macro.

If the value in these cells in the doc 2 < doc 1 / cells in doc 2 are marked in red.
If the value in these cells in the doc 2 = doc 1 / cells in doc 2 are marked in orange.
If the value in these cells in the doc 2 > doc 1 / cells in doc 2 are marked in green.
If the value in these cells in the doc 2 = 0 (empty cell) do nothing.

Thank you all for your help.

Are you talking about different workbooks or different sheets in one workbook?