Storage vs program memory, ROM, RAM - please help me understand
 

I just got my first PPC (Mio A501 running WINCE 5) and am a little confused about the different kinds of "memory" - I would appreciate some help in understanding these various terms (I searched through this forum and on google, but the different things I read just confused me even more...).

The specs from the distributor said "Memory: 64 MB / 1024 MB SDRAM" (which I understand are internal and not expandable), and I got it with a 4 GB external SD card. When I check the Memory (Settings>System>Memory), it shows me under "Main" 2 types of memory: Storage (total: 70.95 MB) and Program (total: 46.16 MB). In addition, under Storage Card, I have 2 options: Mio Recovery (total: 891.81 MB) and Storage Card (total: 3748.66 MB).

I understand the Mio Recovery must be the 1024 MB SDRAM from the specs, and of course the Storage Card is the 4 GB card.

What I don't understand is the Storage/Program memory. If the PPC was supposed to come with 64 MB RAM, why does it show only 46 MB for Program Main Memory? Or is the Main Memory the combination of the Storage + Program? If this is the case, then why is the total 71+46=117 MB, i.e. MORE than 64 MB? And what is the ROM?

Basically, what I want to know is if I got what I was supposed to get, or if I have less memory (46 MB) than I should have (64 MB).

I would greatly appreciate the benefit of your experience to get a better understanding of this. Thank you in advance to whoever can help me out on this!