Whenever I'm asked if the Jewish holidays are coming early or late this year, I promptly answer that they'll be coming on time. And that's partially true. Rosh Hashanah will always arrive on the first day of the Jewish month of Tishrei just as Hanukkah will always begin on the 25th of Kislev.
There are many elements which make the High Holy Days a unique experience. Often, congregations swell to double or triple their usual size, the musical settings of even common liturgy are different, and some might alter their dress by wearing either traditionally all-white garments or more formal wear than they would sport on Shabbat. Some congregations even have unique garments to dress their Torah scrolls in white.