Logic Express 9 is probably missing the same thing Logic Express 8 was missing:
The additional applications, which come with Logic Studio: MainStage, Soundtrack Pro, Waveburner and Compressor.
Some software instruments are missing: the vintage ones (EVB3, EVD6 and EVP88) and Sculpture.
A couple of the effects are also missing: Space Designer reverb (with the Impulse Response Utility), Delay Designer, AD Limiter, Linear Phase EQ, Match EQ, MultiMeter and all Surround plugins.
Additional features that are missing are:
- Support for Logic Nodes (offloading the CPU load to other computers)
- Support for some high-end control surfaces
- Support for DigiDesign/Avid ProTools TDM system
The content is also smaller: the audio effects (3 DVDs) and the JamPacks (3 DVDs) are not included.