No MDIL. NGEN can still JIT for things like cross domain generics and because it loads non-native code, still needs to optimize at run time.
Project N compiles to fully native code, so there can be no JIT, and significantly smarter optimizations can happen since they don't impact performance at runtime.
@Pantaloons: Right on all counts. One clarification: .NET Native and MDIL are orthogonal. MDIL was used in Triton to split NGen into conceptually two pieces: the optimized part (in the Windows Phone Store) and the part bound on the customer's device to the installed Framework.
.NET Native produces completely native binaries. MDIL/Triton produces NGen binaries that still need a runtime and, occasionally, a JIT.
Sorry. Triton is the Windows Phone 8 "Compiler in the Cloud". It basically split NGen into two pieces, allowing the optimization to happen in the Store while the .exe generation happened on the device. The interface between these two halves is MDIL.
Project N compiles to fully native code, so there can be no JIT, and significantly smarter optimizations can happen since they don't impact performance at runtime.