How do you know the difference between oral thrush and BM residue on baby's tongue?

Generally rule of thumb is that if you are able to scrap off from your baby's tongue, it's milk residue. Also, milk residue will only appear on the baby' tongue but thrush will be on the tongue, roof, insides of the cheeks. Do not try to scrap off thrush because if you do, you will find a raw, red area underneath that may bleed.