I will state this as someone who is as anti-Trump as they come:
Hillary's email server was unconscionable. She knew exactly what she was doing and why she was doing it. I believe her having the server was likely be a clear violation of the law, but I am no criminal law expert. I believe there were enough articles written at the time of the various laws she would have violated in conducting government business like that on a private email server.
HOWEVER
Trump did something totally different. He stored highly secretive documents including documents containing intelligence sourced information in a fucking toilet at Mar Lago where every foreign agent known to man would have been actively working as it was a target rich environment. He was asked nicely to return these documents several times. Then legally they demanded he return the information. His attorneys said they returned all the documents they had under oath after conducting a diligent search and still the government found more. Then to figure out who had access to the rooms where this highly sensitive information was stored, they requested electronically stored videos so they could pin point exactly who had access to the various rooms where these documents were stored and he had the fucking pool guy flood the room.
So in summary I can buy the argument that Hillary should also have been prosecuted for some of the bullshit she pulled. But their actions are not equal, similar, or in the same fucking ballpark. Trump's actions are hundreds if not thousands of times worse.