Perfect rhyme is a pattern in which initial consonant sounds of the rhyming words are different, but vowels and sounds following the vowel are identical, as in "moon/June" -- a so-called masculine rhyme consisting of words of one stressed syllable or multisyllabic words with a final stress. Multisyllabic words in which rhyme occurs in a final unstressed syllable are called feminine rhymes: "hassle/castle." Perfect rhyme is intended for the ear, not the eye, and depends on sound, not on spelling.
Slant rhyme is a variant of perfect rhyme in which "rhyming" words are similar in sound, but not identical. In John Donne's poem "The Passionate Shepherd to His Love" contains a well-known slant rhyme: "Come live with me and be my love/And we will all the pleasures prove." "Love/prove" have identical consonants but the vowels, read aloud, are not an exact match.
Eye rhymes are intended for the eye, not the ear. Words in an eye rhyme do not rhyme at all when read aloud, but they appear similar on the page. William Blake's poem "The Tyger" contains a famous eye rhyme: "What immortal hand or eye/Could frame thy fearful symmetry?" The pair "eye/symmetry" suggests a rhyme but when pronounced correctly, the "rhyming" vowel sounds differ.
Rhyme is not confined to the ends of lines. To create a sense of unity and rhythm, rhyming structures can occur both internally and at line end, as in Edgar Allan Poe's "The Bells:" "To the swinging and the ringing of the bells/...to the rhyming and the chiming of the bells." Internal rhyme with repeated meter creates a rhyme pattern called a leonine rhyme (a line similar to the two rhyming lines of a couplet, placed on the same line) as seen in Percy Bysshe Shelley's "The Cloud:" "I bring fresh showers to the thirsting flowers."