Here are some common ones. More will be added in due time
OneKeePass stores all your passwords and other details in a single encrypted file in any place supported by the iOS's Files app or Android supported File Manager - typically called "My Files" or just "Files"
OneKeePass supports the well known KeePass database format KDBX 4.
You can open many databases at the same time.
OneKeePass does not do any automatic synchronization at this time. As the password database is a single file, you can use any of the cloud storage service for the synchronization between devices and also for the backup
Entries are organized so that you can view them as Entry types or Categories or Group tree.
It is just the flattened list of keepass groups instead of a tree/folder like structure
Each entry type has certain set of fields. For example Login entry type include fields like username, password, url etc. OneKeePass supports some built-in standard entry types: Login, Credit/Debit Card, Bank Account and Wireless Router. More standard entry types will be added.
Mobile version does not yet support this. It will be implemented soon.