Does restoring an iPhone to factory settings before a restore from a backup produce a different result than just restoring from a backup? Does restoring an iPhone to factory settings before a restore from a backup produce a different result than just restoring from a backup?

Restore your iPhone, iPad, or iPod to factory settings

Restore your iPhone, iPad, or iPod touch from a backup
No.

Theres not much more to say. The end result will be the same: the device will be restored from a backup.