“Aesthetics” (or “esthetics”) is the term most commonly used to refer to the philosophical study of all forms of art, especially the nature, functions, purposes, and origins of art. Thus the term “aesthetics” is relevant to all the arts, including not only literature but also painting, music, dance, sculpture, etc. Each period in history tends to have a characteristic aesthetic theory that is widely adopted by many people at that time. (For instance, “Romanticism” affected not just literature but also music, painting, etc. William Blake is a good example of a person who was both a Romantic poet and a Romantic painter.) Aesthetics tends to emphasize what is common to all the arts rather than what makes them distinct. For instance, a common assumption of aesthetics has been that the arts share a common focus on producing “beauty,” although the word “beauty” itself is a term that is extremely difficult to define objectively. The attempt to define such ideas objectively has long been one of the goals of aesthetics, and indeed aesthetics has often been understood as the philosophical study of ideas about beauty.
Many recent writers have been strongly opposed to, or critical of, the idea (and ideals) of aesthetics. They have resisted in particular any claims that the art can be (or should be) divorced from politics, economics, or society. One critic of traditional concepts of aesthetics has been Terry Eagleton, in his book The Ideology of the Aesthetic. As his title suggests, Eagleton seeks to show that aesthetic ideas are always affected by politics. According to Eagleton, there can be no non-political, disinterested, objective concept of aesthetics. Early in his book, for instance, Eagleton writes,
The construction of the modern notion of the aesthetic artefact is thus inseparable form the construction of the dominant ideological forms of modern class society, and indeed from a whole new form of human subjectivity appropriate to that social order. But my argument is also that the aesthetic, understood in a certain sense, provides an unusually powerful challenge and alternative to these dominant ideological forms, and is in this sense an eminently contradictory phenomenon. (3)
The term “poetics” refers, in one sense, to the philosophical study of literature. It often refers to ideas about what makes “literature” different from other kinds of writing, such as journalism, scientific writing, technical writing, etc. “Poetics” can involve the study not simply of poetry but indeed of all the various genres of literature, such as epic, the novel, the short story, drama, etc. Sometimes “poetics” can involve issues that are very abstract and theoretical; at other times, however, it can involve issues that are very precise and concrete, such as the meter of a poem or the structure of a sonnet.
“Aesthetics,” then, is the broader of the two terms.