Trump deliberately set out to steal the most sensitive security documents and remove them from the White House. This shit didn't just magically appear in his inbox and he held onto it by mistake. The fact that he hid the stuff and refused to give it up just proves intent.
Clinton had nothing above "classified" on her server, and the handful of documents that were classified, we designated AFTER she had received them.
Trump had SDI Top Secret documents that are never supposed to be viewed outside of a secure room, locked in a basement at a public golf club which is a frequent target of international spies. There is nothing "accidental" in those boxes, there are sets of documents all stamped "TOP SECRET" across every single page.
Not to mention, Trump a long history of flashing national security documents around the dining room at Mar-a-lago, and giving sensitive information to the Russians in the Oval Office.
Last but not least, when a document is "declassified", that 'TOP SECRET' stamp is removed. Trump saying he "declassified" something when he took it, carried no legal weight whatsoever. He has to complete the paperwork before ANYTHING is declassified. This isn't a loosey goosey family firm.