According to Osho, there is no difference: an Upanishad is a timeless, spaceless happening — a love affair between an overflowing master and a totally open disciple. When bliss is ready to shower and receptivity has no fear or reservation, the Upanishad occurs. Labels like ‘ancient’ or ‘modern’ are irrelevant; only the meeting of ecstasy and availability matters.
Upanishads aren’t old or new—they happen anytime a joyful master shares and a fearless, open student receives.