MahaVishnu, who rests on the eternal ocean from his exhalation, unlimited universe expand from his pores. The MahaVishnu then expand himself and enter each universe as the Garbhodakasayi Vishnu.
Garbhodksayi Vishnu - On his naval bramha seat and on that lotus string all the 14 lokas are there in that lotus string.
Shridoksayi vishnu is parmatma.Paramatma sits in the hearts of all living entities, giving direction to them in their material sojourn.