инкрементальный бэкап содержит в себе все предыдущие записи, дифференциальный - только новые с последнего бэкапа
Incremental backups also back up only the changed data, but they only back up the data that has changed since the last backup — be it a full or incremental backup. They are sometimes called "differential incremental backups," while differential backups are sometimes called "cumulative incremental backups." Confused yet? Don't be.