You may have misunderstood.  You usually end up with the same results.

If you itemize, then you enter the mortgage interest and taxes on Lines 10 and 11 of Form 8829 (if you are hitting the $750,000/$1,000,000 limit, then part of it may go to lines 16 and 17).

If you don't itemize, they go on Lines 16 and 17.