hog plum vs wild plum tree

hog plum and wild plum tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
hog plum	Yes	No	No	No
wild plum tree	Yes	No	No	No

As nouns, wild plum tree is a hypernym of hog plum; that is, wild plum tree is a word with a broader meaning than hog plum:

hog plum: small native American shrubby tree bearing small edible yellow to reddish fruit
wild plum tree: an uncultivated plum tree or shrub

Other hypernyms of hog plum include wild plum.

hog plum (noun)	wild plum tree (noun)
fruit of the wild plum of southern United States	an uncultivated plum tree or shrub
yellow oval tropical fruit
small native American shrubby tree bearing small edible yellow to reddish fruit
tropical American tree having edible yellow fruit