mycelium vs plant structure

mycelium and plant structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
mycelium	Yes	No	No	No
plant structure	Yes	No	No	No

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

mycelium: the vegetative part of a fungus consisting of a mass of branching threadlike hyphae
plant structure: any part of a plant or fungus

Other hypernyms of mycelium include plant part.

mycelium (noun)	plant structure (noun)
the vegetative part of a fungus consisting of a mass of branching threadlike hyphae	any part of a plant or fungus