According to the Hindu religious scholars and pundits, the Sātvata-tantra largely describes three totally different aspects or forms of Lord Vishnu as initially as Mahā Vishnu, then as Garbhodakaśāyī Vishnu and next as Kṣīrodakaśāyī Vishnu Vishnu (Paramātmā).
This is mentioned in Gaudīya Vaishnavism that belongs to the school of Vaishnavism. It is to be noted that each and every form largely has a totally different role in the perfect maintenance of the said Universe and its comfortable inhabitants.
As per the legends, Lord Krishna’s plenary expansion largely assumes three Vishnus for material creation. The initial avatar is Mahā Vishnu who is believed to be the creator of the total material energy, called as the mahat-tattva.
The next avatar is Garbhodakaśāyī Vishnu, who is strongly believed to enters into all the universes in order to create successfully diversities in each of them.
The other next avatars is Ksīrodakaśāyī Vishnu, who is also strongly believed to have diffused as the all-pervading Super soul in all the universes in the centre heart of every living being and is largely called as Paramātmā.
It is to be noted that he is greatly present even within the atoms. It is to be remembered that Garbhodakaśāyī Vishnu is the perfect expansion of Mahā Vishnu (that largely means the expansion of Saṃkarṣaṇa of second caturvyūha and later expands from Nārāyana in Vaikunthaloka). This avatar has religious and social significance among the Hindu religious devotees and pilgrims who wholeheartedly worship this particular Lord on auspicious days as per the Hindu traditional calendar.