It’s still interference if it was done in the United States.
They impeached President Trump because he supposedly requested assistance for a foreign government to interfere in the election process. So there is your difference. The request by a foreign entity to interfere. Of course the interference by the DNC , via a law firm hired and paid for by the DNC and the opposition candidate, to dig up dirt on Trump by a foreign entity doesn't count, in the liberal mind. In that instance it warrants a Special Prosecutor to see if he committed any crimes by colluding Russian interference and cost the taxpayers several 10s of millions to prove what was already known, that it was not true.
So yes it in interference, but in the liberal mind that kind of interference is quite okay.
In other words it's a double standard, and they get away with it because the press is in their back pocket.