Difference between IKVM.Reflection.Emit and Mono.Cecil

IKVM.Reflection.Emit has "the ability to read and emit .NET 1.1, .NET 2.0 and .NET 4.0 assemblies (while running on, for example, .NET 2.0).".

Does Mono.Cecil have the same? Are they interchangable for this use case? Are they both supported nowadays? What are key differences between them (in emitting IL)?