When I go into photos, there is a choice of photos, photo stream, albums and places. Photos has all my photographs and they seem to stay there unlike photo stream. When I go into albums there is something called camera roll, I think it has all the same pictures (although I'm not sure there are so many I get confused trying to check back and forth). What is the difference between photos and camera roll? Why do I have two things that, at least to me, seem to be the same?