These classified documents episodes indicate to me that
1) these laws and rules appear to be onerous to understand and to comply with, and
2) there are probably way too many documents that are "classified" that shouldn't be.
Breaking the rules/law should not excused or condoned. What Trump and Biden did was wrong. In my mind, there is no difference between the two situations. Frankly, in and of itself, I don't think either case is a big deal.
The difference is in the reactions to the discovery. The Biden reaction appears to me to be competent and compliant while the Trump reaction appeared incompetent and uncompliant. The former reaction suggests a benign neglect on the part of the Biden team, while the latter suggests a more malign intent on the part of the Trump team.
In my view, the reactions by the teams to this relative nothing burger reflect on the character of the two men and their teams.