IBM BPM and IBM ODM are two IBM complementary solutions.
IBM BPM is about end-to-end process orchestration. a BPM manages orchestration of activities making sure that the righ persons are involved at the righ time with the right documents to complete the activity if required.
IBM ODM is about decision automation. ODM uses business rules and business events all together to capture complex decisions and automate them.
BPM and ODM are complementary in the sense that some decisions inside some end-to-end processes can be automated. In an insurance underwriting process, ODM will be used to automate the elligibility to a specific insurance product as well as its price estimation.