I don't know of a good, clear definition for 'settling with power' that would make it easy for the pilot in the cockpit to say that he was experiencing that or whether he was experiencing vortex ring state.
Most people say settling with power is when power available exceeds power required, but that can happen without the symptoms of vortex ring state.
Unfortunately the terms get mixed up all the time, adding to the confusion.
I avoid the use of the term settling with power as it doesn't add any clarity to the discussion. But that's my personal opinion.
If someone can come up with a clear distinction between the two, I'd be happy to include it in the next edition of the book.