morphological rule vs rule of morphology

morphological rule and rule of morphology both are nouns.

Word	Noun	Adjective	Verb	Adverb
morphological rule	Yes	No	No	No
rule of morphology	Yes	No	No	No

As nouns, morphological rule and rule of morphology are synonyms defined as:

morphological rule and rule of morphology: a linguistic rule for the formation of words

morphological rule (noun)	rule of morphology (noun)
a linguistic rule for the formation of words	a linguistic rule for the formation of words