There are some combinations of discs and players that just don't work.
Best guess in this case:
The discs are far enough off-center that the DVD player can't handle them,
but the PS3 has more 'reach' in sideways movement of its pickup
and therefore Can handle them.
In many instances, an entire batch of discs will be approximately equally off-center,
so you could return them as defective,
but you may have to wait for a better batch to be made.
That could take years, or never happen at all, depending on what it is.
Another possibility of a similar nature and with the same complications for remedy
is that the discs are warped and the PS3 has a better focus range
and so is able to deal with them.
Of course, they could be Both warped And off-center,
making them a real challenge for any player to read.
And as if that wasn't ominous enough, they could have a poor reflective layer,
which would mean the pickup would have to be more sensitive in terms of light intensity.
These are some of the realities of this seemingly perfect technology.