case vs syntactic category

case and syntactic category both are nouns.

Word	Noun	Adjective	Verb	Adverb
case	Yes	No	Yes	No
syntactic category	Yes	No	No	No

As nouns, syntactic category is a hypernym of case; that is, syntactic category is a word with a broader meaning than case:

case: nouns or pronouns or adjectives (often marked by inflection) related in some way to other words in a sentence
syntactic category: (grammar) a category of words having the same grammatical properties

Other hypernyms of case include grammatical category.

case (noun)	syntactic category (noun)
a comprehensive term for any proceeding in a court of law whereby an individual seeks a legal remedy	(grammar) a category of words having the same grammatical properties
a portable container for carrying several objects
a glass container used to store and display items in a shop or museum or home
bed linen consisting of a cover for a pillow
(printing) the receptacle in which a compositor has his type, which is divided into compartments for the different letters, spaces, or numbers
the housing or outer covering of something
the enclosing frame around a door or window opening
an enveloping structure or covering enclosing an animal or plant organ or part
the actual state of things
nouns or pronouns or adjectives (often marked by inflection) related in some way to other words in a sentence
a statement of facts and reasons used to support an argument
a problem requiring investigation
a specific size and style of type within a type family
an occurrence of something
a person who is subjected to experimental or other observational procedures; someone who is an object of investigation
a person requiring professional services
a person of a specified kind (usually with many eccentricities)
the quantity contained in a case
a special set of circumstances
a specific state of mind that is temporary

case (verb)	syntactic category (verb)
enclose in, or as if in, a case
look over, usually with the intention to rob