DDS is mostly focused on communication, using a publisher-subscriber pattern. Until recently, DDS did not support client-server communication (AFAIK there is now a "beta" implementation available).
Client-server communication, beside the sender-receiver pattern, is a big thing in AUTOSAR.
In an automotive stack, communication is just a small part of the overall functionality. Network management, mode management, diagnostics, etc. are all covered by AUTOSAR. Out of the box, DDS only supports Ethernet as the physical layer. For this, the protocol RTPS is defined within the DDS Context.
AUTOSAR, on the other hand, supports all relevant bus systems in the automotive domain: CAN, LIN, FlexRay, and Ethernet.
DDS beats AUTOSAR when it comes to the support for "quality of service".
The DDS standard documents are made of untagged text, which is a problem for an integration in an automotive development process. Requirements tracing is bigger than you might think.