IT IS really confusing: the two words are mostly misused by average people.
libel is totally different from slander and to identify such difference it is necessary to note that libel is a contumely or reproach, published to the defamation of the government, of a magistrate or a private person, while slander is defamation by word spoken.
The word 'slander' is the general and original word for all kinds of defamation, and at an early day in the history of the common law the term applied both to oral and written defamations of character.
In modern usage, it has been limited to defamation by words spoken, and in this sense may be defined as the speaking of base and defamatory words, which tend to the prejudice of the reputation, office, trade, business, or means of getting a living of another.
Libel is the printed or written declarations of one person against another, while slander is defined to be oral or spoken defamatory words used by one person against another.
Libel is defined to be a malicious defamation, expressed either in printing or writing, or by signs and pictures, tendering either to blacken the memory of one who is dead, or the reputation of one who is alive and thereby exposing him to public hatred, contempt and ridicule.
Libels taken in their largest and most extensive sense signify any writings, pictures, or the like, of an immoral or illegal tendency. Considered particularly as offences against the public peace, they are malicious defamations of any person, made public either by printing, writing, signs, or pictures, in order to provoke him to wrath, or expose him to public hatred, contempt, or ridicule.
The direct tendency of these libels is the breach of the public peace, by stirring up the objects of them to revenge and perhaps to bloodshed.
From the different modes in which a libel may be conveyed, a distinction has been made between a libel in writing, and one without writing.
Others define libel as "a censorious or ridiculing writing, picture or sign, made with a mischievous and malicious intent towards government or individuals."
"Any writing, picture or other sign tending, without lawful excuse, to injure the character of an individual, by subjecting him to ridicule, contempt or disgrace."
Libel is also defined as any representation in writing calculated to create disturbances, to corrupt public morals, or to lead to any act which, when done, is indictable.
The gist of the offence of libel is the publication of something, which tends in contemplation of law to affect injuriously the peace and good order of society because it injuriously affects the reputation, memory, or business of individuals.
Therefore, false, defamatory words, when written, constitute a libel, and, when spoken, a slander.