There are a couple of differences, if I understand DPOS correctly:

1. A miner needs to trust a delegate in DPOS while a miner joins a stake pool in POR - there is no trust.  A miner can monitor the pool and leave if the pool misbehaves.

2. The major difference is that ONE delegate signs a block at a time in DPOS while ALL pools sign each and every block in POR.  This is critical b/c this allows detection of multiple voting and bad behavior of the pools.  Is there any mechanism in DPOS to defend against N@S?