I don't know the difference, but I would think the junior is geared toward kids, whereas the regular is geared towards adults.
You could get delivery confirmation and a tracking number when you send it, and I guess insurance if you want too.
I believe it takes a couple of weeks before my fiance and I got our papers. Possibly a little longer, i'm not sure.
We also photocopied everything just in case it did get lost, we had proof we went it.