thallus vs plant structure

thallus and plant structure both are nouns.

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

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

thallus: a plant body without true stems or roots or leaves or vascular system; characteristic of the thallophytes
plant structure: any part of a plant or fungus

Other hypernyms of thallus include plant part.

thallus (noun)	plant structure (noun)
a plant body without true stems or roots or leaves or vascular system; characteristic of the thallophytes	any part of a plant or fungus