Is there a way to use conditional formatting to search two lists of names,
and highlight the differences by only highlighing those with last name
differences. (My spreadsheet contains over 250 names)

Example:
Column A:
Jones, Dave
Smith, Bob
Brown, Sally
White, Mary

Column B:
Jones, Dave V.
Smith, Bob A.
White, Mary

I am looking for a conditional formula that would highlight Mary White in
column A as the only different one between the two lists.

Please help.