phrase structure vs syntax

phrase structure and syntax both are nouns.

Word	Noun	Adjective	Verb	Adverb
phrase structure	Yes	No	No	No
syntax	Yes	No	No	No

As nouns, phrase structure and syntax are synonyms defined as:

phrase structure and syntax: the grammatical arrangement of words in sentences

Other synonyms of phrase structure include sentence structure.

phrase structure (noun)	syntax (noun)
the grammatical arrangement of words in sentences	studies of the rules for forming admissible sentences
	the grammatical arrangement of words in sentences
	a systematic orderly arrangement