George Papadopoulos pled guilty to a single charge of making a false statement to the FBI. He was not charged with so-called “collusion” because no such crime exists in American statutory law, except in anti-trust matters. It has no application to elections and political campaigns.
It is not a crime to talk to a Russian. Not that the media would ever understand that. They have never managed to point to a single statute that makes “colluding” with a foreign government in a political campaign a crime, likely because it does not exist in the criminal codes.