What is the difference between a metaphor and a simile?

Similes and metaphors are used by writers to describe and they compare how one thing is similar to another. For example, instead of saying ‘the boy had blue eyes’ a writer might compare the colour of those eyes to an intriguing, deep blue lake. As you can see, these comparisons make writing interesting and give stories depth. 
Although similes and metaphors are both used to compare, they are not the same and you need to make sure you know the differences between them.
Metaphors
In a metaphor, one thing becomes or is another thing.
·    His eyes are deep blue lakes
·    Her hair is silk
·    He was a bull in a china shop
·    The world is a stage
The words ‘is’ and ‘are’ make it seem like a transformation has taken place and produce powerful images.
Similes
In a simile, one thing can only be ‘like’ another thing. The words ‘like’ and ‘as’ can always be used to identify when a writer is using a simile.
·    His eyes are like deep blue lakes
·    Life is like a box of chocolates
·    He was as strong as an ox
In turn, similes can seem a little less stylish or powerful than metaphors because their objects don’t ‘transform’ into another thing. The ‘like’ or ‘as’ in them always keeps a distance between the things being compared.
However, this doesn’t mean that metaphors are ‘better’ than similes. In The Yearling, by Marjorie Kinnan Rawlings, the simile is used to good effect and makes a comparison that wouldn’t work with a metaphor. “The water made a sound like kittens lapping”. The sound gives the water a soft, comforting feel. Imagine if she’d used the metaphor “the water was the sound of the kittens lapping”. It doesn’t quite work, does it? Sometimes, that powerful ‘transformation’ of a metaphor can make things a little confusing and you need the distance of a simile to keep things clear.
Test
Using a metaphor, then a simile, compare the colour of your hair to something else like yellow wheat, gold threads or black ink. Make sure to check you’re using the right words: ‘is’ and ‘are’ for metaphors, ‘like’ and ‘as’ for similes.