This episode's headline: A World Apart; Big Apple Ban; Fuming over Ads; Stepping Aside. The guests include In Washington: ALKER MERRYMAN, Tobacco Institute; IRVIN RIMER, American Cancer Society; In New York: JOSEPH PUDER, Americans for a Safe Israel; EMMANUEL SIVAN, Hebrew University of Jerusalem; Dr. STEPHEN JOSEPH, New York City Health Commissioner; In Dallas: MILE SAHLIYEH, North Texas State University; REPORTS FROM NEWSHOUR CORRESPONDENTS: JUNE MASSELL. Byline: In New York: ROBERT MACNEIL, Executive Editor; In Washington: JIM LEHRER, Associate Editor