Andrew Johnson was impeached over the Tenure of Office Act. Congress decided that they could dictate to the President who he could assign to executive positions. The President had grown tired of Edwin M. Stanton and his policies, as a hold over Secretary of War under Lincoln. He appointed none other than Ulysses Grant, General Commander of the Union Armies in his place. He impeachment started soon thereafter. The nation had just finished a Civil War, emotions were high, the country was badly injured.
In contrast we have the Trump impeachments. The second was after he already was voted of office. The first was over a phone call to a foreign leader. The majority of Senate determined his motive on the call was at least ambiguous enough not to prove intent. Not in the same ballpark as the Johnson impeachment or Clinton’s trolling the Whitehouse for feminine company and getting caught.