Metaphor, simile, and analogy - What's the difference?

Here are some tips on how to differentiate between these seemingly very similar concepts:

http://www.copyblogger.com/metaphor-simile-and-analogy-what’s-the-difference/

http://thewritersbag.com/writing-rules/metaphor-simile-or-analogy

Both sites are also worth checking out for the tips they give on writing in general.