hardsub vs hard subtitle

hardsub and hard subtitle both are nouns.

Word	Noun	Adjective	Verb	Adverb
hardsub	Yes	No	No	No
hard subtitle	Yes	No	No	No

As nouns, hardsub and hard subtitle are synonyms defined as:

hardsub and hard subtitle: (often plural) a subtitle whose text is irreversibly merged in original video frames.

hardsub (noun)	hard subtitle (noun)
(often plural) a subtitle whose text is irreversibly merged in original video frames.	(often plural) a subtitle whose text is irreversibly merged in original video frames.