VIENNA — Despite some remaining differences, a deal has been reached with Iran that will allow the U.N. nuclear agency to restart a long-stalled probe into suspicions that Tehran has secretly worked on developing nuclear arms, the U.N. nuclear chief said Tuesday.The news from International Atomic Energy Agency chief Yukiya Amano, who returned from Tehran on Tuesday, comes just a day before Iran and six world powers meet in Baghdad for negotiations and could present a significant turning point in the heated dispute over Iran's nuclear intentions.