R' Eliezer says: From the time the Temple was destroyed Shavuos is like the Sabbath.  Rabban Gamliel says: Rosh Hashanah and Yom Kippur are like the festivals.  The Sages, however, do not agree with either of the two. Rather, Shavuos is like the festivals; Rosh Hashanah and Yom Kippur are like the Sabbath.