Metaphor is implied comparison between 2 objects that are basically different, but in reality have something in common. It has: A -the tenor, B - the vehicle.
Formula: A is B. Here we don't use like or as.
Simile we can find with the help of linking words: like, as, to resemble, to appear and others. It is the imaginative comparison of 2 unlike objects that belong to different classes.
Formula: A is like B.
Personification is giving attributing qualities, abilities or characteristic features of human-being to animals or lifeless objects, making abstract objects behave as alive.
- Personification creates a visual imagery in a manner so beautiful, that you are tempted to imagine what you read.
- The use of this literary device gives a break from the monotonous language that you may be used to reading all the time.
- By giving human qualities to an object, personification serves to emphasize that object, to give the object its own identity, and explain its place in the piece of literature.
- The use of personification also enables the object, action, or concept that is personified, to communicate with the reader.(http://www.buzzle.com/articles/what-is-personification.html)