Answer:
According to experts, at birth the baby's brain contains around 100 billion neurones. An amazing fact is is that the first three years we have up to twice neurones synapses as we will have in adulthood, which is amazing. The second year, the amount of neurones is about the double than the first year, and by the third year we already have an 80% of neurones we will have in adulthood.
So, basically, the different in the amount of neurones is not that big, but synapses processes is, that's why in childhood we are more creative, because our brain is having an incredible and amazing amount of synapses, more than an adult brain.