When the meanings of 'consonance' and 'alliteration' are explained, it can be perplexing as to why the two would differ when they're rather similar. The English language is a tricky one, where there are all kinds of writing styles and rules that make it what it is. The best way to be able to tackle a complex spot in the English language, is to explore it further and apply it as often as possible to get the hang of it. Practice, after all, makes perfect. To make things a little easier, let's take a look at the definitions of consonance and alliteration to begin with.
► "Mary's mother makes marvelous meatballs."
► "Blondie's blueberries bloomed and blossomed."
► "Crabs, crickets, and crocodiles are creepy creatures."
► "How much wood would a woodchuck chuck,
If a woodchuck would chuck wood?
A woodchuck would chuck all the wood he could chuck,
If a woodchuck would chuck wood."
► "Whitney whistles at wheels and whales."
► "The swan swam over the pond. Swim swan swim! Swan swam back again. Well swum swan!"
► "I'll swing by my ankles,
She'll cling to your knees.
As you hang by your nose,
From a high-up trapeze.
But just one thing, please,
As we float through the breeze,
Don't sneeze." - The Acrobats (Shel Silverstein)
► "He gives his harness bells a shake
To ask if there is some mistake.
The only other sound's the sweep
Of easy wind and downy flake." - Stopping by Woods on a Snowy Evening (Robert Frost)
► "If you are a dreamer, come in,
If you are a dreamer, a wisher, a liar,
A hope-er, a pray-er, a magic bean buyer...
If you're a pretender, come sit by my fire
For we have some flax-golden tales to spin.
Come in! Come in!" - Invitation (Shel Silverstein)