HTML vs hypertext markup language

HTML and hypertext markup language both are nouns.

Word	Noun	Adjective	Verb	Adverb
HTML	Yes	No	No	No
hypertext markup language	Yes	No	No	No

As nouns, HTML and hypertext markup language are synonyms defined as:

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

Other synonyms of HTML include hypertext mark-up language.

HTML (noun)	hypertext markup 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