How MEF is different from DI/IOC?

They do overlap each other somewhere. But end goal of both of these concepts are completely different. To understand these 2 concepts we will take a scenario. We have 2 requirements:

1. The application should be a tired application and each tier should be decoupled from each other for better reusability and maintainability.
2. The application should provide a facility of exporting data in to different formats. External vendors should be able to plug in their own mechanism into the application.

For requirement 1 , goal is decoupling while for requirement 2 goal is extensibility.

	DI/IOC	MEF
Decoupling	YES
Extensibility		YES
Integrate Known Things	YES
Integrate UnKnown Things		YES
Automatic discovery		YES
Registration	YES
Discovery		YES
Compile Time	YES
Run Time		YES

In DI/IOC registration of classes is done in configuration file while in MEF automatic discovery take place.  So that DI/IOC is compile time and MEF is runtime.

Here for Decoupling you can use Unity Application Block and Windsor Container framework or anything similar.