SB 1.3 - Rāma, Balarāma and Kṛṣṇa
(18) The Lord appeared as King Rāma with a green complexion of fresh durvā grass. He appeared during the Tretā yuga of the 24th yuga cycle of Vaivasvata era. In order to please the demigods, He exhibited super human powers by controlling the Indian ocean and then killing the demon Rāvaṇa. His show of great power can be seen even today at Sethubandha. Sometimes the demons and atheists become vary famous due to advancement of material civilization and they challenge the established order of the Lord. Different classes of human beings are accommodated in different planets for particular purposes mentioned in the codes of the Lord. Thus attempting to go to the other planets by material means is a challenge to the established order. This was done by Rāvaṇa also who wanted to deport ordinary men to the planet of Indra without consideration of the necessary qualifications. He challenged Lord Rāma and kidnapped His wife, Sītā. Rāma took up Rāvaṇa’s challenge and killed him. Just as the Lord can make gigantic planets float in the air, He prepared a stone bridge on the sea without any supporting pillar. This is a display of the power of God. Rāma is considered Vāsudeva, Lakṣmaṇa is Saṅkarṣaṇa, Bharata is Pradyumna and Śatrughna is Aniruddha. In Padma Purāna, Rāma is considered as Nārāyaṇa with Lakṣmaṇa as Śeṣa, Bharata as conch and Śatrughna as cakra.
(19, 20) The Lord advented Himself as Lord Balarāma and Lord Kṛṣṇa in the family of the Yadus, and removed the burden of the world. The specific mention of the word bhagavān in this text indicates that the Balarāma and Kṛṣṇa are original forms of the Lord. Kṛṣṇa, dark in complexion with two and four hands, appeared with Devakī as mother and Vasudeva as father. Lord Kṛṣṇa is not an incarnation of the puruṣa, but directly the original Personality of Godhead, and Balarāma is His first plenary manifestation. Some explain that Garbhodakaśāyī Viṣṇu took a black and white hair from His head, and these became Kṛṣṇa and Balarāma. This is not correct.
Balarāma appeared from two mothers, Devakī and Rohiṇī, and one father Vasudeva. He had a white complexion like new camphor and wore dark blue cloth. He is Saṅkarṣaṇa, who becomes Śeṣa. Śeṣa is of two kinds: He who holds up the universe is called Saṅkarṣaṇa because Saṅkarṣaṇa empowers him (a jīva). Taking the form of the bed (as īśvara, not jīva), He identifies Himself as a friend and servant of Viṣṇu.