That's not a question.

> Is there a difference between 'belief' and 'knowledge'?

Yes. Knowledge cannot be wrong, beliefs can. A consequence of this is that true knowledge doesn't actually exist, but beliefs can become sufficiently reliable that calling them knowledge is a pretty reasonable approximation.

> Why does the universe exist?

We don't know.

> why is there something rather than nothing

That is a different question. We actually do know the answer to that: it's because "nothing" is unstable.