What is the difference between consanance and alliteration? Please provide examples.

While cosonance and alliteration are sound devices that
depend upon the repetition of cosonant sounds, they differ in the placement of these
sounds. 

Consonance is the
repetition at close intervals of the final consonant sounds of accented syllables or
important words. For example, in Macbeth's soliloquy after this wife's death, he
reflects that all the world is a stage upon which eacher person is merely an actor "That
struts and frets his hour upon the stage." The ending sounds of the words
that, struts and frets are an
example of consonance.

Alliteration,
on the other hand, is the repetition at close intervals of the
beginning cosonant sounds of accented syllables or important words.  For instance, the
poet e.e. cummings makes use of alliteration to move the lines rapidly along in his poem
"maggie and milly and molly and may." Here the /m/ moves the first line rapidly.  Here
are some other examples:mapmoon,
kill-code,
preach-approve. 

On
occasion, there is alliteration of vowels, as well. Important words and accented
syllables beginning with vowels are considered alliterate as far as they have the same
lack of an initial consonant sound.  For example, in the repetition of the //
in "Inebriate of
Air am I."

Interestingly alliteration
and cosonance can be combined, as in such phrases as "thick and thin,"  "kith and kin,"
and "alas and alack." These two forms of repetition of cosonants work to add sound to
the reader, pleasing the ear, adding emphasis to the words,  as well as advancing lines
of poetry and lending to the poem structure and  consistency
.

Source:  Literature: Structure, Sound, and
Sense.  Wadsworth: Cengage Learning.