A simile is a comparison between two unlike objects using the words like or as in the sentence.
" Over time, many similes that we use in everyday language have become clichés, for example, as quiet as a mouse, as soft as a feather, as green as grass."
A metaphor compares two dissimilar things suggesting that one thing is another, not using the words like or as.
"A famous metaphor is from William Shakespeare's As You Like It, Act II, Scene VII, when the character Jaques recites the soliloquy, "All the world's a stage/And all the men and women merely players."
I am a rainbow (metaphor), bright and shining like the sun (simile)