Plantae vs plant kingdom

Plantae and plant kingdom both are nouns.

Word	Noun	Adjective	Verb	Adverb
Plantae	Yes	No	No	No
plant kingdom	Yes	No	No	No

As nouns, Plantae and plant kingdom are synonyms defined as:

Plantae and plant kingdom: (botany) the taxonomic kingdom comprising all living or extinct plants

Other synonyms of Plantae include kingdom Plantae.

Plantae (noun)	plant kingdom (noun)
(botany) the taxonomic kingdom comprising all living or extinct plants	(botany) the taxonomic kingdom comprising all living or extinct plants