vascular plant vs plant life

vascular plant and plant life both are nouns.

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

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

vascular plant: green plant having a vascular system: ferns, gymnosperms, angiosperms
plant life: (botany) a living organism lacking the power of locomotion

Other hypernyms of vascular plant include flora, plant.

vascular plant (noun)	plant life (noun)
green plant having a vascular system: ferns, gymnosperms, angiosperms	(botany) a living organism lacking the power of locomotion