I have attached two poems for you to consider. "To Autumn" is by Keats, "I Wandered Lonely as a Cloud" They are popular works from each author that focus on nature.
In your comparison you should note similarities and then differences in form, diction, point of view, tone, mood, voice, presentation of theme, meter, figurative language (simile, metaphor, figure of speech, personification).
You might even read literary criticism of each to determine how they were received in their own eras and how the poems have stood the test of time and why. You might look for the motivation behind the poems.
Good luck! Hope these resources help!
John Keats tended to use nature in his poetry, but his poems did not generally revolve around nature. "Ode to a Nightengale" is one of his most famous poems, and that is an example of a Keats' poem that is solely nature-based. "Bright Star," a famous Keats sonnet, is a love poem but uses nature as a device to express his emotions. See the second link regarding the film Bright Star, about John Keats.
William Wordsworth, on the other hand, wrote about nature itself, glorifying it through his poetry. A good site to look at for your own understanding of Wordsworth is provided below.
While doing this project, keep in mind that John Keats was dedicated to Latin, mythology, classical literature (such as Dante and Homer), and Shakespeare. The use of nature in his poetry stems from his personal surroundings. Wordsworth saw nature on a more intimate, spiritual level; that is, however, not to decrease the importance of Keats' nature- work.
This is a great project: have fun doing it, and I encourage you to seek out more information about these two men. Outside of class, they can be far more interesting than within the realms of a research project.