headroom vs dynamic headroom

headroom and dynamic headroom both are nouns.

Word	Noun	Adjective	Verb	Adverb
headroom	Yes	No	No	No
dynamic headroom	Yes	No	No	No

As nouns, headroom and dynamic headroom are synonyms defined as:

headroom and dynamic headroom: the capacity of a system to reproduce loud sounds without distortion

headroom (noun)	dynamic headroom (noun)
the capacity of a system to reproduce loud sounds without distortion	the capacity of a system to reproduce loud sounds without distortion
vertical space available to allow easy passage under something