Microsoft Excel 2011 – Sort and Match Two Different Columns

I have a sheet with two different columns that display two different prices. I want to sort the sheet by these two columns to see all the prices that do not match. I want to list all the prices that do not match first.

Example:

Price A-A Price A-B
$ 19.99 $ 19.99

$ 14.99 $ 14.99

$ 17.99 $ 16.05

$ 18.99 $ 17.50