Full migration will perform a full content migration between devices, including settings, alarms, accounts, files, calendar, media, SMS, MMS, notes and additional preferences.
Migration is limited to transaction between same OS, meaning iOS to iOS and Android to Android. Note that when performing migration transfers, the target device must meet the source device OS version or later.
Same goes for Backup and Restore, if you perform a migration Backup, it can only be restored to same OS.
Selective transfer will transfer the chosen content between all device OEM's and OS's.