shampoo vs hairdressing

shampoo and hairdressing both are nouns.

Word	Noun	Adjective	Verb	Adverb
shampoo	Yes	No	Yes	No
hairdressing	Yes	No	No	No

As nouns, hairdressing is a hypernym of shampoo; that is, hairdressing is a word with a broader meaning than shampoo:

shampoo: the act of washing your hair with shampoo
hairdressing: care for the hair: the activity of washing or cutting or curling or arranging the hair

Other hypernyms of shampoo include hair care, haircare.

shampoo (noun)	hairdressing (noun)
the act of washing your hair with shampoo	care for the hair: the activity of washing or cutting or curling or arranging the hair
cleansing agent consisting of soaps or detergents used for washing the hair	a toiletry for the hair

shampoo (verb)	hairdressing (verb)
use shampoo on (hair)