bedding plant vs garden plant

bedding plant and garden plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
bedding plant	Yes	No	No	No
garden plant	Yes	No	No	No

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

bedding plant: an ornamental plant suitable for planting in a flowerbed
garden plant: any of a variety of plants usually grown especially in a flower or herb garden

bedding plant (noun)	garden plant (noun)
an ornamental plant suitable for planting in a flowerbed	any of a variety of plants usually grown especially in a flower or herb garden