In comparing and contrasting "Horses" by Edwin Muir and "Pike" by Ted Hughes, what strikes me first is the sound of the poems, which are very different.
Where Hughes' "Pike" is written in free verse, Scottish poet Muir's "Horses" has a steady rhyme, as well as a rhythm that creates a sense of movement in the poem that mimics (for me) the loping motion of horses as they gallop. The rhyme allows for a musical quality as one reads it aloud. It is easy to understand T.S. Eliot's praise for Muir's work, in that Muir...
...will remain among the poets who have added glory to the English language.
The rhyme easily catches one's ear as shown in the following lines:
They seem terrible, so wild and strange,
Like magic power on the stony grange.
Perhaps some childish hour has come again,
When I watched fearful, through the blackening rain...
The poem is written in rhyming couplets—pairs of lines that rhyme with each other on the last word of the line (called "end rhyme"): strange and grange, and the near-rhyme (also called "half rhyme," "slant rhyme" or "inexact rhyme") of again and rain.
Besides the difference in structure, I am also struck by the difference in tone—how the author feels toward his subject—which also creates, in these poems, the mood (how the reader feels).
"Pike" is especially impactful with the description of pike: fish with long, razor-sharp teeth. For those of us who have seen them, they are frightening creatures (perhaps only slightly less fear-inspiring than piranhas); Hughes captures their ability to create this feeling of fear as he describes the demise of three pike they kept in a tank when he was young, as they ate each other...till only one was left:
One jammed past its gills down the other's gullet:
The outside eye stared: as a vice locks-
The same iron in this eye
Though its film shrank in death.
Even Hughes' description of pike in the pond at evening personifies them as evil creatures. However, Muir's horses—while they seem frightening to the author—they also inspire a sense of "magic" and mystery.
...Like magic power on the stony grange.
The sounds of the poem are different; the mood and tone of the poems are different. What they share is the authors' masterful use of the language using imagery. Hughes writes...
...The jaws' hooked clamp and fangs.
...Their hooves like pistons in an ancient mill...
Without seeing the fish or horse before us, they come alive with the authors' ability to create images in our minds that are vivid and full of life.