The first is libel. Libel means that the defamatory statement was made in printed form. The second kind is what's known as slander. Slander means that the defamatory statement was spoken. Regardless of whether it's libel or slander, it could be what's known as defamation per se.
While defamation depends upon what particular state law says about what qualifies as defamation per se, typically they involve a few different categories. The first that would qualify for defamation per se is when someone makes a false statement accusing another of a serious crime. The next category is when they make a false statement intending to injure a person in his or her profession.
The third category is when they make a false statement suggesting that a person has a loathsome disease. Now, loathsome is a term of art in the area of law that goes back many, many years, but in today's day and age it means something that we would equate to AIDS, for example, HIV or some other kind of disease that people would not want to encounter.