Difference Between CD-DA image on a CD-R and CD-RW

I am using a SONY DVP-S335 DVD player.
this device is not supposed to read CD-Rs with CD-DA images,
and it does not.
However it reads CD-RW cd’ies with no problem, even though
the vendor specificaly claims is not supposed to work.
Does anyone knows why.

By the way the same CD-RW are not readable using
SONY CDP CD Players.