Why CC AND Moon+

Hi all,

Newbie question to which I cannot find a clear answer:
Why do people use both CC and Moon+?

I can find lots of information about how to use them, but not why both. It seems that Moon+ will access a dropbox folder and sync reading state, etc.

I'm wondering if it works okay to use calibre on my PC to get books converted and into that dropbox folder, but then just use Moon+ to read from my Android devices (a new Onyx C67ML Carta 2 and a Nexus 6P).

Any insight would be greatly appreciated. Thanks!