There are four stanzas in Parts I and II, five stanzas in Part III, and six in Part IV. The stanzas all contain the same basic structure: there are nine lines, with a rhyme scheme of aaaabcccb. This strong emphasis on rhymes helps to give the poem the feeling of an ancient tale.
This is the "1833 version"
In the poem, it used a lot of poetic/literacy techniques. Such as : Personification - "beard barley" (part 1, stanza 4, line 2) the barley doesn't have a beard but it has sort of long wheat-looking type that looks like a beard.
Pathetic Fallacy - "In the stormy east-wind straining" (Part 4, stanza 1, line 1) *Pathetic Fallacy is when the human feelings/emotions are the same as the weather, art etc
Similie - "Like to some branch of stars we see" (Part 3, stanza 2, line 2) Basically the bridle of the horse was sparkling, like the starry skies.
* A similie is when you compare one thing with another, oftenly use the word "like" or "as"
There's more personification - "And the silent isle imbowers" (Part 1 , stanza 2, line 8)
I think there's also a assonance (I'm not sure though) - Whillows whiten, aspens "quiver" (Part 1, stanza 2, line 1) and Little breezes dusk and "shiver" (Part 1, stanza 2 line 2) "Quiver" and "Shiver" are the assonance that are use.
And if you notice there's a rhyme scheme which is "aaaabcccb"
extensive use of alliteration in the poem....
He uses repitition of the last words in each stanza. He uses rhyme extensively and also uses alliteration :) . Sources : Pinno