Pteridospermopsida vs class Pteridospermopsida

Pteridospermopsida and class Pteridospermopsida both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pteridospermopsida	Yes	No	No	No
class Pteridospermopsida	Yes	No	No	No

As nouns, Pteridospermopsida and class Pteridospermopsida are synonyms defined as:

Pteridospermopsida and class Pteridospermopsida: extinct gymnosperms most of Carboniferous to Jurassic: seed ferns and allies

Pteridospermopsida (noun)	class Pteridospermopsida (noun)
extinct gymnosperms most of Carboniferous to Jurassic: seed ferns and allies	extinct gymnosperms most of Carboniferous to Jurassic: seed ferns and allies