hair of the head
髪 centers on the hair that grows on a person's head, as opposed to facial or body hair.
髪 is the modern Japanese simplified form of 髮. Both combine 髟 (hair) with a phonetic component: 犮 in the traditional form and 友 in the simplified form. The character originally referred to hair on the head.
The top component 髟 looks like long flowing hair, and the bottom 友 suggests a friend. Imagine a friend with long, beautiful hair that you can't help but notice.
For ハツ, imagine a hat sitting on top of a head of hair: hat -> ハツ, and the hat covers the hair on the head.
hair (on the head)
hair (on the head); (a) hair
hair style; coiffure; hairdo
black hair
blond hair; blonde hair; golden hair
forelock; bangs
white hair; grey hair; gray hair
hair (on the head)
hair dyed brown; brown-dyed hair
hair
(having a) haircut; hair-cutting; hair-dressing
long hair (usu. of a man)
short hair
by a hair's breadth; in the nick of time; touch and go; close call; critical moment
silver hair; gray hair; grey hair
hair on the back of one's head
hair's breadth
haircut
immediately; instantly; with nary a pause; without a moment's delay
cutting of hair (to a short length); haircutting