cryptogam vs plant life

cryptogam and plant life both are nouns.

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

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

cryptogam: formerly recognized taxonomic group including all flowerless and seedless plants that reproduce by means of spores: ferns, mosses, algae, fungi
plant life: (botany) a living organism lacking the power of locomotion

Other hypernyms of cryptogam include flora, plant.

cryptogam (noun)	plant life (noun)
formerly recognized taxonomic group including all flowerless and seedless plants that reproduce by means of spores: ferns, mosses, algae, fungi	(botany) a living organism lacking the power of locomotion