flower girl vs helper

flower girl and helper both are nouns.

Word	Noun	Adjective	Verb	Adverb
flower girl	Yes	No	No	No
helper	Yes	No	No	No

As nouns, helper is a hypernym of flower girl; that is, helper is a word with a broader meaning than flower girl:

flower girl: a young girl who carries flowers in a (wedding) procession
helper: a person who contributes to the fulfillment of a need or furtherance of an effort or purpose

Other hypernyms of flower girl include assistant, help, supporter, female child, girl, little girl.

flower girl (noun)	helper (noun)
a young girl who carries flowers in a (wedding) procession	a person who helps people or institutions (especially with financial help)
a woman who sells flowers in the street	a person who contributes to the fulfillment of a need or furtherance of an effort or purpose