To compare two columns in Excel row-by-row, write a usual IF formula that compares the first two cells. Enter the formula in some other column in the same row, and then copy it down to other cells by dragging the fill handle (a small square in the bottom-right corner of the selected cell). As you do this, the cursor changes to the plus sign.
To find cells in the same row with different content, simply replace “=” with the non-equality sign:
As you have probably noticed, the formulas from the previous example ignore case when comparing text values, as in row 10 in the screenshot above. If you want to find case-sensitive matches between 2 columns in each row, then use the EXACT function: