金剛經纂要刊定記 7.32

7.32

偈云下。標真化異也。如來即是法身，本來不動猶若虛空，故不同化身隨機來去，此非異而異也。

From "The verse says..." onward indicates the difference between the real and the transformed. The Tathāgata is precisely the dharmakāya, fundamentally unmoving like empty space; therefore it is not like the transformation body coming and going in accordance with capacities. This is difference within non-difference.