grass pink vs garden pink

grass pink and garden pink both are nouns.

Word	Noun	Adjective	Verb	Adverb
grass pink	Yes	No	No	No
garden pink	Yes	No	No	No

As nouns, garden pink is a hypernym of grass pink; that is, garden pink is a word with a broader meaning than grass pink:

grass pink: European pink cultivated for its very fragrant pink or rosy flowers
garden pink: any of various flowers of plants of the genus Dianthus cultivated for their fragrant flowers

Other hypernyms of grass pink include pink.

grass pink (noun)	garden pink (noun)
an orchid	any of various flowers of plants of the genus Dianthus cultivated for their fragrant flowers
European pink cultivated for its very fragrant pink or rosy flowers