Perceptual rendering tries to compress the source gamut into the destination gamut in such a way that the overall color relationships are preserved. It is designed to do non-linear compression in alignment with the non-linear behavior of the human visual response.
Absolute rendering by contrast attempts to reproduce all colors numerically (destination = source). This can cause unexpected results if the source gamut is larger than the destination.
Generally speaking the perceptual intent is the better choice for photographs where absolute might do a better job with corporate colors.