I know that my other staff members have been to these types of gatherings, much different from convention gatherings, but I recently attended one to experience it for myself. And from what I felt and saw, it is much, much different. Much more laid back, casual, just occupying space in public. I love seeing the interactions with the cosplayers and the public when the public has the "right of way" (versus at conventions when the attendees/cosplayers have the "right of way"), especially when they wanted photos of us and even a video segment.
At first, it was only myself, the organizer, and a couple of cosplayers. But by the end of the day we were to about twenty people, and we did various things like doing a photo shoot near the river, playing chess and checkers at the mall, and playing music on the top floor of the parking garage. Unlike most convention gatherings, most of this was planned at the last second, and usually they work out for the most part.
It was nice to sit back and be with some old friends and new acquaintances. I hope to see you all in the near future.