Softly
Part of speech: adverb
Definition: In a soft manner; gently. Not loudly; nearly inaudible.
Example sentence: But I, being poor, have only my dreams; I have spread my dreams under your feet; Tread softly because you tread on my dreams.
Quietly
Part of speech: adverb
Definition: In a quiet manner.
Example sentence: Feelings are more dangerous than ideas, because they aren't susceptible to rational evaluation. They grow quietly, spreading underground, and erupt suddenly, all over the place.