singular form vs descriptor

singular form and descriptor both are nouns.

Word	Noun	Adjective	Verb	Adverb
singular form	Yes	No	No	No
descriptor	Yes	No	No	No

As nouns, descriptor is a hypernym of singular form; that is, descriptor is a word with a broader meaning than singular form:

singular form: the form of a word that is used to denote a singleton
descriptor: the phonological or orthographic sound or appearance of a word that can be used to describe or identify something

Other hypernyms of singular form include form, signifier, word form.

singular form (noun)	descriptor (noun)
the form of a word that is used to denote a singleton	a piece of stored information that is used to identify an item in an information storage and retrieval system
	the phonological or orthographic sound or appearance of a word that can be used to describe or identify something