plant life vs acrogen

plant life and acrogen both are nouns.

Word	Noun	Adjective	Verb	Adverb
plant life	Yes	No	No	No
acrogen	Yes	No	No	No

As nouns, acrogen is a hyponym of plant life; that is, acrogen is a word with a more specific, narrower meaning than plant life:

plant life: (botany) a living organism lacking the power of locomotion
acrogen: any flowerless plant such as a fern (pteridophyte) or moss (bryophyte) in which growth occurs only at the tip of the main stem

plant life (noun)	acrogen (noun)
(botany) a living organism lacking the power of locomotion	any flowerless plant such as a fern (pteridophyte) or moss (bryophyte) in which growth occurs only at the tip of the main stem