There are billions of Brahmanda material universes all originating from the Body of Maha Visnu. Inside each Brahmanda universe is a secondary smaller material universe where Garbhodakashayi Visnu, Lord Brahma and the 14 different planetary systems exist. This inner material secondary universe is therefore surrounded by and encased with an outer Brahmanda universe's 7 massive material layers, earth, water, fire, air, sky, false ego, mahat-tattva.

The names of the 14 material planetary systems are mentioned below in painting.

It is important to understand our single secondary material universe is situated deep within the surrounding massive Brahmanda as also seen in painting below.

There are billions of these massive Brahmanda universes, all coming from the Body of Maha Visnu as seen in painting below.

Each Brahmanda has their own "secondary inner material universe" deep inside the surrounding Brahmanda universe.

And each inner  secondary universe has their own planetary system, that are all in different sizes, our secondary universe has 14 different Planetary Systems.

This means there are billions of Garbhodakashayi Visnus, billions of Lord Brahmas, billions of Lord Sivas, billions of all the demigods in each material secondary universe that are deep inside their outer Brahmanda greater universe.

However,  there is only one Maha Visnu in the material creation, as also seen in painting below.