I have a dataset like this in Excel:

```
A B
1 X X
2 X Y
3 Y X
4 Y Y
```

I want to set up conditional formatting such that rows 1 and 4 will be highlighted as green because their A and B cells are the same. The same formatting should highlight rows 2 and 3 red because their A and B cells are different.

How can I do that?

I know I can create a new column using the formula `A1=B1`

to generate `TRUE`

or `FALSE`

, then use the new column for highlighting, but I don't want to do an extra step.