Someone Explain Why Michael Cohen is in Prison and Trump Isn’t?

I’m not a lawyer so maybe someone can explain it to me. How is it that Michael Cohen is in prison but Donald Trump isn't his cell-mate? I mean, part of what Cohen is in prison for is "election fraud". Specifically, he paid hush money to a porn star and a Playboy model. But it wasn't HIS money, it was Trump's. And HE didn't bang the porn star, Trump did. Cohen, the poor schlub, probably didn't even get to smell Donald's finger.

I mean, granted, I can understand Cohen’s guilt inasmuch as he was a party to election fraud. But he was only the intermediary, right? I can't understand why the guy who actually paid the hush-money to the porn stars that he needed to hush (again because HE had sex with them) gets to walk around, remain president and claim vindication based on the same investigation that got his lackey, Cohen, three years in prison. I can’t make it add up.

I threw it out on the air this morning for anyone to explain. However, the Trumpites in the audience were, how would you say it...oddly silent.
It reminds me of when the world found out that Trump told Billy Bush that he went up to women and grabbed them by the genitals because he's famous. Billy Bush got fired from Good Morning America. Trump got elected president. Wow.

What a weird country the United states has become.