Well, a metaphors is basically when you say it is that thing. So, I am a sneaky snake. Well obviously I am not a snake, Or am I? Na, any way, a simile is when you say it is like that thing. So, I am like a sneaky snake.
Some metaphors:
It is raining cats and dogs
Let's talk about the elephant in the room (Or there is an elephant in the room)
His eyes were ice as he stared at her
I am Fit as a fiddle
He said it with the confidence of someone caught with their hand in the cookie jar, in a cookie factory, and his pants are on fire
Some smilies
it was As light as a feather
He was eating like a Pig
Her glare was as sharp as daggers
They grinned like a cat
It was as dead as a dead thing