What Soft and Hard clipping?
Depending on their design, analog circuits can clip in a way that is not sudden, but gradual, leaving rounded rather than flat tops on the waveform. Likewise, the onset of clipping is gradual rather than sudden, so their is no sudden transition to clipping. This is known as soft clipping and is less intrusive than the hard clipping sounds produced by digital devices. This type of distortion in small doses can actually benefit certain sounds, adding character.
Soft clipping is typical of tube and FET circuits.