Every project has an outcome, or better yet, a "desired outcome" as David Allen suggests.
Originally Posted by silvine
The outcome is what you intend to achieve, when you can mark that project complete.
Projects are generally reviewed weekly in your Weekly Review, and will have a completion within the next 12 months or so.
Goals are higher up on the Horizons of Focus in GTD. They live at the 30,000 level and reflect your 1-2 year Goals and Direction. For most people, reviewing those about quarterly seems to work well.
You'll find a good explanation of this too in the free article called "Levels of Your Work" found here: http://www.davidco.com/free_articles? and in our GTD System Guides, with examples and suggestions for what to review when: https://secure.davidco.com/store/cat...ES-p-16204.php