In an interview situation, you have a very limited amount of time to show people what you really bring to the table. You can be very well prepared for this with great stories, anecdotes about how your experience matches to their needs and you can solve what they're talking about. But at the same time, if you've had a chance to talk to somebody who might be your future co-worker or your future supervisor or boss in a more informal setting, it's a very different game.