HTML vs hypertext mark-up language

HTML and hypertext mark-up language both are nouns.

Word	Noun	Adjective	Verb	Adverb
HTML	Yes	No	No	No
hypertext mark-up language	Yes	No	No	No

As nouns, HTML and hypertext mark-up language are synonyms defined as:

HTML and hypertext mark-up language: a set of tags and rules (conforming to SGML) for using them in developing hypertext documents

Other synonyms of HTML include hypertext markup language.

HTML (noun)	hypertext mark-up language (noun)
a set of tags and rules (conforming to SGML) for using them in developing hypertext documents	a set of tags and rules (conforming to SGML) for using them in developing hypertext documents