Under UPOV 78, we can keep and save seeds without necessarily asking permission from the breeder. The breeder could not have access to our harvests. He could not have surveillance over our harvests. We could actually save seeds to the extent the breeder could not.
UPOV 91 has to...even our harvests. The breeder can put surveillance on it.
But under UPOV 78, I don't think the breeder's right to encroach upon our harvest or exercise so much of a degree of surveillance and control is guaranteed.