In your case Gallery is "Photo Album" - they are the same thing. It's just that you (or antother site admin) has renamed it to Gallery, which is a perfectly fine thing to do.
So, go ahead and add members' photos to the Gallery I think! You could for example create a new album (or folder) for each member in there and let them upload into it. You can even control the permissions so that each member only has write access to their own album.