Juxtapositions | Metaphors

Juxtaposition:

• the act of positioning close together (or side by side); "it is the result of the juxtaposition of contrasting colors"
• a side-by-side position
  wordnetweb.princeton.edu/perl/webwn
• A placing or being placed in nearness or contiguity, or side by side, often done in order to compare/contrast the two, to show similarities or differences; An absence of linking elements in a group of words that are listed together; Two or more contrasting sounds, registers, styles etc. ...
  en.wiktionary.org/wiki/juxtaposition

• an act of comparing two things, especially in a way that suggests connection between them or to distinguish them
  www.statemaster.com/encyclopedia/Clerks

Simile:

• gure of speech that expresses a resemblance between things of different kinds (usually formed with `like' or `as')
  wordnetweb.princeton.edu/perl/webwn
• A simile is a figure of speech comparing two unlike things, often introduced with the words "like" or "as". ...
  en.wikipedia.org/wiki/Simile

• A figure of speech in which one thing is compared to another, in the case of English generally using like or as
  en.wiktionary.org/wiki/simile
• Simile is a comparison of two dissimilar objects that uses the words like or as. See, for example, Karen Connelly's description of herself in "Touch the Dragon": "As the country pulls out from under me, I overturn like a glass of water on a yanked tablecloth, I spill. ...
  www.pearsoned.ca/text/flachmann4/gloss_iframe.html
• a figure that explicitly expresses the comparison, often signaled by "like" or "as"
  www.indiana.edu/~bestsell/glossary.html
• A comparison, usually using "like" or "as", of two essentially dissimilar things, as in "coffee as cold as ice" or "He sounded like a broken record." The title of Ernest Hemingway's "Hills Like White Elephants" contains a simile. (Compare with Metaphor.)
  www.gale.cengage.com/free_resources/glossary/glossary_s.htm

source: google define

In mybelieve, Juxtaposition is an act or instance of placing close together or side by side