I feel a slight pain on the top of my head.
The top of a baby's head is still soft.
頭頂 specifically means the top of one's head (anatomical), while 頂点 is a general term for the highest point of anything, concrete or abstract.
parietal lobe
top of the head; crown; parietal region
parietal bone
temporoparietal junction; TPJ
Compound of 頭 (とう, 'head') and 頂 (ちょう, 'top, summit').