Why my baby's anterior fontanelle smell different than the other body parts? the smell is not that bad but im confuse what make it smell like that?

No scientific reason: I can't think of a scientific reason for this, nor do I know the age of your baby. It is not unusual for babies to develop a "cradle cap" rash which can have a distinct smell. Are there scaly patches on the babies scalp? If you see nothing, then I would not give it a second thought. In fact, the best thing for the " cradle cap" rash is to ALSO do nothing! Enjoy your baby!