Final answer:
Similes use words such as 'as', 'like', or 'than' to compare two things, while metaphors directly compare two things without using any comparison words.
Step-by-step explanation:
The first comparison, 'The moon was as round as a dinner plate,' is a simile because it uses the word 'as' to make a comparison between the moon and a dinner plate. Similes use words such as 'as', 'like', or 'than' to compare two things.
The second comparison, 'The storm was a real nightmare,' is a metaphor because it directly compares the storm to a nightmare without using any comparison words.
The third comparison, 'I ran like the wind,' is a simile because it uses the word 'like' to compare the act of running to the wind.
The fourth comparison, 'The meal was a work of art. It was almost too pretty to eat,' is a metaphor because it compares the meal to a work of art without using any comparison words.
Learn more about Similes and Metaphors