The two Jewish days or periods of commemoration, Passover and Sukkot, are at different ends of the calender, but are closely related. Both involve the Biblical story of Exodus, and both involve activities designed to remind Jews of their history while also celebrating their deliverance.
Passover, of course, is the day, always in the Spring, when Jews gather to recite the Biblical story of their enslavement in Egypt, their deliverance from brutal captivity, and their trek through the desert on their way to the land promised them by God. Every Passover, the Haggadah is read, the story recited individually by everyone at the Sedar table, and certain foods associated with the story are ritualistically prepared and consumed. For example, matzoh is eaten during the Passover period as a reminder that the Hebrews fleeing Egypt were forced to remove their bread from ovens prematurely and were prepared without yeast. While matzhol is eaten, regular bread and anything else made with yeast is forbidden.
While Passover is observed in the Spring, Sukko, the Feast of the Tabernacle, is always five days after Yom Kippur, the Jewish day of atonement, the holiest in the Jewish calender, which is always in the early Fall. Whereas Yom Kippur is a solemn period of reflection and fasting, Sukkot is a celebration of the harvest, and is much more joyous. What connects Sukkot to Passover is that both are reflections of the Exodus. In addition to celebrating the harvest, during Sukkot observant Jews construct shelters on their propery of branches, twigs, palm fronds, and other natural materials. The purpose of the shelter is to commemorate the temporary dwellings in which the Hebrews lived during their years in the desert. As such, Sukkot embodies both a commemorative element -- the construction of the shelter to symbolize the way Jews lived during their 40 years wandering in the desert -- and the practical way they harvested their fields.
Jewish customs and practices, then, are closely related to Passover and Sukkot during their periods of celebration. From prayer services specific to each period to modifications in lifestyle and diet in accordance with Jewish law as set forth in the Bible, many Jews continue to practice their religion in accordance with Biblical mandates.