What is the main difference between Neoclassicism and the Romantic period when it comes to poetry?
Neoclassical poetry tended to be written in a much more elevated manner, using classical models such as epics, odes, and pastorals. The aesthetic approach of neoclassicism was descriptive, seeking to represent the world with the utmost fidelity and accuracy. Unlike the Romantics, there was no sense of fusing one's imagination with the world to create new forms of expression. It is not surprising that neoclassical poetry achieved prominence during the Enlightenment, with its strongly empirical spirit. The workings of the imagination were felt to be dark, barbarous, and largely unfathomable. They were not, then, thought to be a suitable instrument for poetic composition.
The Romantics, by contrast, were keen to establish a poetic voice based on simple language. This was the manifesto of Wordsworth and Coleridge that they famously set out in the Advertisement to Lyrical Ballads. The very title of this collection must have seemed quite shocking at the time, almost oxymoronic. Ballads were songs or verses associated with the common people. As such, they were deemed unworthy of the lyricism of high art. Wordsworth and Coleridge, however, were effectively saying poems that dealt with the concerns of ordinary people, written in a language they could understand, could indeed aspire to the condition of music just as much as the more refined work of the neoclassicists.
There was more than just a hint of snobbery in all of this. In the waning hours of neoclassicism's heyday the writing of poetry was widely thought a suitable occupation solely for gentlemen and should deal with elevated themes culled from antiquity, history, and mythology. When Keats published "Endymion," a scathing review appeared in Blackwood's Magazine, contrived to be both condescending and brutally snobbish. As well as patronizing Keats as "Johnny Keats," part of a "Cockney" school of poetry, the reviewer lamented the fact that farm servants and married ladies were increasingly starting to write poetry. Even footmen were composing tragedies!
This is an oversimplification, but the main difference between Neoclassicism and Romanticism is that the former emphasized structure, objectivity, and restraint, while the latter emphasized imagination, subjectivity, and emotion.
Neoclassical poets such as Alexander Pope admired the Classical Age and therefore tried to emulate the features of that age. In Pope's An Essay on Criticism, he writes about the benefits of ordering and restraining creativity. When the inspiration hits, Pope argues the proper poet (or critic) will utilize control rather than let his or her imagination run wild:
Tis more to guide than spur the Muse's Steed;
Restrain his Fury, than provoke his Speed;
The winged Courser, like a gen'rous Horse,
Shows most true Mettle when you check his Course.
Romantic poets such as William Wordsworth emphasized the individual, subjective experience. Wordsworth was more concerned with imagination and emotion. In the preface to Lyrical Ballads, he famously wrote:
For all good poetry is the spontaneous overflow of powerful feelings: and though this be true, Poems to which any value can be attached were never produced on any variety of subjects but by a man who, being possessed of more than usual organic sensibility, has also thought long and deeply.
Although it is not always the case, Neoclassical poetry tends to be rooted in Classical forms and themes of structure and restraint. Romantic poetry tends to focus on the emotional and imaginative experience of the individual. Another way to say this is that the Neoclassical poet might say "this is how poetry should be" while the Romantic poet might say "this is what poetry means to me."