Amitayus belongs to the Yoga Tantra. His colour is red and he always holds the long-life vase that sometimes has an Ashoka-tree branch, the tree of life, coming out of it. The vase contains water, saffron, and nectar pills, food of the gods that confers immortality. Amitayus is a central deity in longevity rituals and contemplations.
Amitayus is distinguished from Amitabha Buddha Amitabha is always depicted in Dhyana-mudra, with a pindapatra, and he is a nirmana-kaya,a Buddha with monastic robes. While Amitayus is also shown in Dhyana-mudra, but with an amrita-kalasha filled with ambrosia, nectar pills and topped by a branch of Ashoka tree, symbolizing long life with full of health. He is a sambhoga-kaya with royal ornaments. The conceptualization of enlightenment as a flash of illumination led to the apotheosis of infinite as Amitabha. An important function of deities is healing and long life. His healing aspect was apotheosized Amitayus. Amitayus Buddha is invoked to cure a person in ill-health, but on death he went to the world of Amitabha. Amitabha resides in the Western Paradise of Sukhavati but Amitayus has no specific heaven and he is placed on an abstract plane.
Thus Amitayus or Infinite Life is a deity parallel to but independent of Amitabha. In the Tibetan tradition he has been clearly distinguished from Amitabha, both iconographically and philosophically. In India, in the Buddhists Sanskrit literature, Saddharmapundarika-sutra, and Sukhavati-vyuha,Amitabha and Amitayus are mentioned indiscriminately. Even Sadhanamala, has not clearly distinguished them. The Tibetan Buddhist tradition credits the distinctive entity of Amitayus to the Indian teacher Tiphu who revealed it to Ras-chun-grags-pa who diffused his worship in the Land of Snows. In the Japanese tantric denomination of Shingon, Amitayus (Japanese Muryoju) belongs to the Garbhadhatu-mandala and Amitabha (Japanese Amida) to Vajradhatu-mandala. Lokeshchandra, assigned distinction between Amitabha and Amitayus to the seventh century A.D.
The thangkas and sculptures of Amitayus Buddha and properly worshipped in Tibet, Mongolia, China, Korea and Japan mainly because of the firm faith of the people in his powers of prolonging life, as the absolute symbols of Infinite (amita) Life (ayus). A sacrament to Amitayus Buddha is celebrated on an auspicious day for life everlasting. Devotees throng to the temple to receive blessings. Every village performs it at least once a year for the life of the community.
In this black esoteric painting Amitayus Buddha is seated in vajraparyankasana on a lotus base. He holds the long-life vase with an Ashoka tree emerging from the top. His colour is red, he wears ornaments of Bodhisattva, a crown, floral silk scarves and dhoti. There is an aureole, surrounded with plants, and halo behind his body and head, respectively. Amitabha Buddha is seated on top centre in clouds with rainbow light. The bottom centre depicts auspicious offerings, placed on a lotus emerging from a lake. The painting is brilliantly drawn and painted; it is very much suitable for sadhana and practice of Amitayus Buddha.
This description is by Dr. Shailendra K. Verma. His Doctorate thesis being: "Emergence and Evolution of the Buddha Image (From its inception to 8th century A.D.)".