>> a similar level of diversification and musical difference, at least to those with ears to hear <<

My ears must be playing up. 'Elphin Knight'; 'Scarborough Fair'; 'Sing Ivy': different tunes, different texts, different plotlines.

cf "minutia of nuance in a single phrase"

...not the same thing at all. Nor is improvisatory jazz. Nor is the reinterpretation by a single musician or group of their own compositions (though I'd be interested to hear those Gong recordings, of course).