Enlightenment Literature was heavily indebted to the contemporary trends in philosophical and scientific thinking: as such, it emphasised logical and rational discourse, as a way of understanding the world. Philosophers like Kant and Voltaire opposed both faith based governance and morality, in favour of reason. This led to a heavy emphasis on epistolary literature, like Richardson's Clarissa, an abundance of Odes to figures like Newton and the first dictionaries and encyclopaediae.
In contrast, the Romantic period kicked back against this. Instead of reason and Kantian ethics, the Romantics found morality to be mutable and individualistic; the scientific values of the enlightenment and the industrial revolution were disavowed in favour of the naturalism of Wordsworth's 'Prelude' and Keats' 'To Autumn.' Natural spaces in these poems are liminal, exploring the boundaries of human endevour, where Enlightenment works, satires, political essays, etc., firmly entrenched themselves in society. In short, Romanticism seeks to find the role of the individual in a chaotic and mutable world, while the Enlightenment looks for the empirical and justifiable strictures of such a world.
Some more interesting ideas here:
https://medium.com/illumination/enlightenment-and-romanticism-89f9d65f186d
