soft pedal vs foot lever

soft pedal and foot lever both are nouns.

Word	Noun	Adjective	Verb	Adverb
soft pedal	Yes	No	No	No
foot lever	Yes	No	No	No

As nouns, foot lever is a hypernym of soft pedal; that is, foot lever is a word with a broader meaning than soft pedal:

soft pedal: a pedal on a piano that moves the action closer to the strings and so soften the sound
foot lever: a lever that is operated with the foot

Other hypernyms of soft pedal include foot pedal, pedal, treadle.

soft pedal (noun)	foot lever (noun)
a pedal on a piano that moves the action closer to the strings and so soften the sound	a lever that is operated with the foot