What's the difference between insusurration and susurrus?

Insusurration

Definition:

• (n.) The act of whispering into something.

Example Sentences:

Susurrus

Definition:

• (n.) The act of whispering; a whisper; a murmur.

Example Sentences:

• (1) From this distance – approximately 900 metres – the susurrus of slowly turning blades sounds like a distant country road, minus the intermittent heavy rumble of semitrailers that are a fixture in less isolated rural areas.