The last time I went, I saw this Icon of the Dormition of Mary. The docent explained that this particular Icon portrays the Eastern Orthodox doctrine on the Assumption of Mary. The Dormition of the Theotokos and the Assumption of Mary, are both celebrated on August 15. We are celebrating the same event. However, the Orthodox church teaches that Mary died a natural death, but that her soul was received by Christ, and that her body was resurrected on the third day, at which time her soul was taken up, bodily into heaven.
Roman Catholics believe that Mary was "assumed" into heaven in bodily form. Pope Pius XII, defined the docrine of the Assumption, in Apostolic constitution, Munificentissimus Deus (1950).
Orthodox and Roman Catholics see the role Mary has played in Jesus' life. We can see that she who played the most prominent part of His life, would be resurrected, like all of us, but more uniquely, as befitting her role. She was the first person to say "yes", and for this reason should be especially honored.
Read Romans 8: 28-30.