Hello,
the difference between OOoDirect and JODConverter lies primarily in the way Office processes are handled. OOoDirect only works with one Office process instance that is either started externally (on boot of the server) or by Alfresco once during startup of the subsystem. JODConverter is able to dynamically manage Office process instances (one or more), e.g. able to recover from process crashes and restart the process instances after a certain amount of work to combat memory leakages. For Enterprise deployments, JODConverter should almost always be used.
Regards
Axel