Final answer:
Sunken fontanelle is a condition where the soft spot on a baby's head appears to be sunken inwards, while bulging fontanelle is a condition where the soft spot on a baby's head appears to be bulging outwards.
Step-by-step explanation:
In newborns, the skull contains fontanels, which are soft spots between the bones that allow for flexibility during birth and enable the skull and brain to grow after birth. Sunken fontanelle is a condition where the soft spot on a baby's head appears to be sunken inwards, while bulging fontanelle is a condition where the soft spot on a baby's head appears to be bulging outwards.