Allusion and similes are both common literary elements used to enhance the quality of a story. While statements of allusion may appear on the surface to mirror similes, they have different purposes. An allusion is simply a brief mention of a person, place or event. A simile is a statement comparing similar qualities between two different things.
Examples of Allusion and Similes
Describing a character as being "honest like Abe Lincoln" is an allusion used to emphasize the character's honesty by comparing him to a historical figure known for his honesty. "Like" and "as" are key words in a simile. "Her eyes glistened like the noon day sun" is a simile. It strengthens the point that the character has beautiful eyes by comparing them to the glistening sun.