In literature what is the difference between form and content?

Form can refer to both broad and specific types of literature. For example, form could refer to whether or not you are writing a novel, poetry, play, etc. It can also refer to things within these categories. Within poetry, for example, you have the haiku, the sonnet, free verse, blank verse, etc. Even within sonnets you have Shakespearian and Petrarchan. Content is simply what is actually written. At times, form can dictate content. The sonnet form, for example, usually contains idealized romance or a deep non-romantic affection. At times, however, authors may choose to use unlikely content within a certain form to achieve an ironic effect. In "The Waste Land" for example, T.S. Eliot briefly slips into a sonnet form to relate a story of debased and mechanical love. Readers who are familiar with the sonnet form notice the contrast, and this foregrounds the perversity of Eliot's characters.