From high level 5.x kernel is:
- “Ready “Ready for the future, data compatible with the past”past”: Content Content Repository accessible via Public API & REST API v2 (full read & write support)
- “Full Symfony2 access”: Symfony2 Full-stack as the framework, extended with eZ Publish features
- DemoBundle front-end on top of eZ's Symfony2 stack (read only)
- “Dual “Dual kernel: Full code and data backwards compatibility”compatibility”: 5.x stack is not fully functional on its own, it's combined with 4.x ("legacy stack") in a "Dual-kernel" setup (see developer section for more) to be able to provide all features you would expect; this is fully exposed to website developers as well that want/need to take advantage of legacy stack, 5.x stack or both.