Throughout the span of American history, there have only been two presidential impeachments. Both Bill Clinton and Andrew Johnson were impeached, which simply means that they were accused of "high crimes and misdemeanors" as specified in the U.S. Constitution.
However, these two impeachments were different in several key ways. The impeachment of Bill Clinton was more unpopular with the public and involved far more salacious details than that of Andrew Johnson. In addition, the vote count in the two impeachments was significantly different.
Popular Opinion Concerning the Two Impeachments
Andrew Johnson, who assumed the presidency upon the death of Abraham Lincoln, was an unpopular president in the North because of his pro-slavery views. Even though he was the only Southern senator not to walk out of Congress when the Confederacy was formed, he remained sympathetic to the South. After the war, Johnson was adamantly opposed to any laws that would grant rights to the freed slaves or punish white men who had fought for the Confederacy.
Congress deliberately passed the "Tenure of Office Act," which prohibited him from firing cabinet members without the Senate's approval, in the hopes that he would break the law. He proceeded to do so by dismissing his Secretary of War. This caused the House of Representatives to issue Articles of Impeachment calling for his removal from the presidency.
The impeachment of Andrew Johnson was greeted with vast approval in the North. Most citizens there were tired of Johnson blocking Reconstruction policies and wished to see him lose all power to do so.
In contrast, the impeachment of Bill Clinton was unpopular throughout large sections of the country. Only areas of high conservatism tended to look on it favorably. This is because in more liberal areas, the crimes Clinton was charged with did not seem significant. He was accused of lying under oath, but since the lies had concerned his private life and not any matter connected to his policies, many people believed that the questions had been inappropriate to begin with.
Here we can see a great irony of history. In Clinton's case, Congress did not pass a law specifically so that he would break it. Yet they had done so for Andrew Johnson. It is easy to see that Johnson's situation resembled entrapment, while Clinton's did not. Nevertheless, it was Bill Clinton who received the most public sympathy during his impeachment.
Scandal Level of the Two Impeachments
Another reason why the impeachment of Bill Clinton was less popular than that of his Civil War predecessor was because of the nature of the crimes alleged in each case. Clinton's impeachment was rife with titillating details about his private life, including his relations with women other than his wife. The public, rightly or wrongly, did not generally regard his alleged crimes as being very serious. In Andrew Johnson's case, there was no sexual scandal attached to the charges leveled at him. Johnson was accused of a dry, technical crime that most people outside of Congress didn't even understand well. What they did know was that they disapproved of his policies. The Northern public (the only public that counted in some sense, since Southern states had not yet been re-admitted to the Union) cared about Johnson's obstruction of Reconstruction plans designed by the Radical Republicans, who were popular in the North at this time.
The Senate Vote in the Two Impeachments
Both Bill Clinton and Andrew Johnson had trials in the Senate, as provided for by the U.S. Constitution. To be removed from office, a two-thirds "guilty" vote in the Senate would be required. Andrew Johnson escaped this fate by a single vote, and so goes down in history as the U.S. president who has come closest to being forcibly removed from office. (For those thinking about Nixon at this point, keep in mind that he resigned the presidency. He was neither impeached nor removed.)
In the impeachment of Bill Clinton, the vote count was not nearly so close. 67 guilty votes were required to remove him from office; for the worst of the charges he received only 55. On another count the vote was 50 to 50, meaning that there wasn't even a majority for conviction.