Goofy, the only person that can declassify documents is POTUS....not VPOTUS and certainly not a Senator who would have to make a concerted effort to skirt the security protocols to get copies or originals of classified documents. Read that as Biden knew what he was doing when he did it as a Senator in clear violation of Federal law. As much as I was skeptical about the whole inadvertant excuse, which legally makes no difference, he simply has no such excuse for the docs he took as a Senator. So yes, the circumstances surrounding Trump and Biden are different.....it is much worse with Biden because he doesn't even have the ability to use the excuse that he declassified documents. He had no ability to do so.
And yes, POTUS can declassify any document with a wave of his hand even if that is not how it's usually done. Bear in mind that POTUS does not even have a security clearance. Our Constitution POTUS the sole ability to declassify even if you don't like it. I know your civics education is lacking but c'mon man!