Nicholas Grossman compares Trump's mishandling of classified material with Hillary's, and shows how what Trump did was different and worse.
https://grossman.arcdigital.media/p/ok-fine-what-about-hillary
A "Hillary rule" like David French argued would not be appropriate.
Clinton was Secretary of State when she had her private server and was carrying out her official duties. Trump was a former president who had no business keeping classified materials.
Hillary's server circumvented government procedures, but email servers have security protections and keep records. To that end the DOJ found no evidence that her server had been hacked. In contrast, Trump kept classified materials in unsecured areas of Mar-a-Lago where people without security clearances frequented. And US counterintelligence was concerned about foreign operations targeting Mar-a-Lago.
Relevant law was changed from a misdemeanor to a felony and signed by Trump himself between the time of Hillary's misbehavior and Trump's.
A "Hillary rule" would involve the DOJ behaving improperly. Comey made several public statements before the election where he editorialized her behavior beyond the facts and the law, and without any new incriminating evidence.
Hillary complied with a House committee subpoena and turned over emails. The FBI found no evidence she intentionally deleted emails to obstruct. Trump instead did not turn over all the requested documents, ignored a letter requesting the rest, didn't comply with a grand jury subpoena, and signed a letter falsely certifying all documents were turned over, resulting in the eventual search.
Trump's conduct around national security has been consistently worse and sloppier.
Trump has not been cooperative, has lied about the investigation, and has openly criticized investigators.