order Isoetales vs plant order

order Isoetales and plant order both are nouns.

Word	Noun	Adjective	Verb	Adverb
order Isoetales	Yes	No	No	No
plant order	Yes	No	No	No

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

order Isoetales: aquatic or marsh-growing fern allies; known to have existed since the Cenozoic; sometimes included in Lycopodiales
plant order: the order of plants

order Isoetales (noun)	plant order (noun)
aquatic or marsh-growing fern allies; known to have existed since the Cenozoic; sometimes included in Lycopodiales	the order of plants