ok, I'm a newbie here, so this is probably a dumb question, but here goes: What is the differnce between a small ring agenda and the agenda pm. the LV website lists them as being the same size(4x6) and both have 6 rings. Also, are the refills interchangeable? For the record, i am looking at a small ring damier and the only refills I see are for the pm size. will they work?