loud pedal vs sustaining pedal

loud pedal and sustaining pedal both are nouns.

Word	Noun	Adjective	Verb	Adverb
loud pedal	Yes	No	No	No
sustaining pedal	Yes	No	No	No

As nouns, loud pedal and sustaining pedal are synonyms defined as:

loud pedal and sustaining pedal: a pedal on a piano that lifts the dampers from the strings and so allows them to continue vibrating

loud pedal (noun)	sustaining pedal (noun)
a pedal on a piano that lifts the dampers from the strings and so allows them to continue vibrating	a pedal on a piano that lifts the dampers from the strings and so allows them to continue vibrating