Just note some subtle differences to our responses, and be aware how Excel handles these.
- I assumed you were talking about future dates (so A1 would hold future dates). JoeMo assumed past dates (so A1 would hold past dates). Whichever one is bigger needs to be first in the subtraction expression.
- I included a date range, so order of the Conditional Formatting rules does not matter. JoeMo only checks the end date, so order does matter. And note that when entering CF rules, Excel does it in reverse order so that the LAST condition you enter is the 1st priority. The good news is that if you do happen to enter them in the wrong order, it is easy to edit the rules and re-order them.