The album was recorded in 1976, i.e. around the same time as their official live album Playing the Fool BUT while the latter was recorded on their European tour that year, this here is taken from one US concert at Calderone Theater NY July 3, 1976 and there lies the difference.
The official one is much closer to the studio albums it takes tunes from, it has much of the medieval, jazz, folk, classic elements that made up the bands unique sound while the US version just rocks out - in a good way. The tunes and the musicianship stay intact, just everything just hits much harder and the musicians themselves seem to have much more fun.
It is a sign of the strength of the material and a proof of the fantastic playing of that band that both approaches in concert work - personally I even like the US one better because they venture further from the known studio versions and they risk more...and that is what progressive rock was all about.
Like attack waves performed by the two saxophone players who duel over the experimental guitar, the assaults come and fade with moments of calm and melodic beauty in between. It is rough and spontaneous most of the time but also almost ambient in other parts. The concept is great and never dull, although the execution may have required a bit more of fine tuning to make this a really great album instead of just being very interesting.