According to the Orthodox tradition, August 15 is celebrated as the�Dormition/Departure of the Theotokos. The Catholic Church celebrates the day as the Assumption of Mary. Though, both the celebrations allude to the same event, the inner meaning and focus is very different. The orthodox view is that Mary died a natural death and her soul was received by Son and on the third day, after her death, her body was transported to heaven.
The Catholic Church's dogmatic definition is given by Pope Pius XII in Munificentissimus Deus (in 1950).HH declared “By the authority of our Lord Jesus Christ, of the Blessed Apostles Peter and Paul, and by our own authority, we pronounce, declare, and define it to be a divinely revealed dogma: that the Immaculate Mother of God, the ever Virgin Mary, having completed the course of her earthly life, was assumed body and soul into heavenly glory�.Pope�Pius XII�deliberately left open the question of whether Mary died before her Assumption though the more common teaching of the early Fathers is that she did.
The Catholic Church gives more importance to the assumption, i.e., the acceptance of Mary into heaven. But the Orthodox Church focuses on the "Soonoyo". Soonoyo means departure (or Vangippu in Malayalam) and Dormition means falling asleep. Soonoyo is a common word connoting death. The assumption of Mary is not recorded in any of the texts used for service by the church, though some references are made in some of the songs used in the service. It is believed by some that Soonoyo is the earlier tradition than the Assumption. The Syrian Church while not denying the Assumption gives paramount importance to Soonoyo.
H G Dr. Gabriel Mar Gregorios (1997).Kurishum Thejassum
Justice Benjamin Koshy (2010).Blessed Virgin Mary
Zach George Arapura