Differences Between WP_Query() and get_posts() for Querying Posts?

Question

What are the differences between using WP_Query() and get_posts()? Which is better to use in what case and why?

Answer 1

Well, get_posts() actually instantiates a new WP_Query object, so if you're comfortable using WP_Query directly, don't even bother with get_posts(); get_posts will only return the results from the database, whereas WP_Query gives you the whole functionality of the class.

Answer 2

In addition to what John P Bloch says, you can modify the default WP_Query object (instead of creating an new instance) before it runs with it's class methods and an action hook, reducing the db calls you make.