This Cosmos thing is pretty big, and so far has been proven to be bigger than any human’s brain.
There is disagreement about whether “Cosmos” is a container for “Universe” or vice versa.
The words are used more or less synonymously, but some scientists and philosophers believe there are multiple universes, not just the one we know, and so it’s a little clumsy to refer to Everything as The Universe.
Cosmos is conceivably less confusing, implying a sense of Allness, or Oneness.
Which, in the current discussion, is increasingly The Point.
In these posts, for the moment, we’ll use Cosmos, Everything, and Nature as the same thing.