General questions
What is a personal gallery, and how is it different from a shared album?
The short answer
A shared album shows the event's photos to everyone who has access, while a personal gallery gathers the photos a specific guest appears in or that are relevant to them.
The shared album is the snapshot of the whole event: the dance floor, the atmosphere, the group shots, the general moments. It works well as a more open memory of the night.
The personal gallery is a more private experience. It is there to save the guest from searching through hundreds of photos and to give them a place that feels like their own.