If AccurateRip shows "No tracks could be verified as accurate", why still shows "You may have a different pressing from the one(s) in the database"?

How does AccurateRip determine which one a CD is? Depend on CRC or something else?

I wanna sent the CD ripping data to complete AccurateRip's database, but I notice "It is recommended data is submitted no sooner than once a month".
This means AccurateRip can store the ripping data until you send them, right?

Wish for the answers, thanks a lot and sorry for my terrible English:blush: