Phaeophyceae vs class Phaeophyceae

Phaeophyceae and class Phaeophyceae both are nouns.

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

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

Phaeophyceae and class Phaeophyceae: brown algae; mostly marine and littoral eukaryotic algae

Phaeophyceae (noun)	class Phaeophyceae (noun)
brown algae; mostly marine and littoral eukaryotic algae	brown algae; mostly marine and littoral eukaryotic algae