Whats the difference between MSIL and CIL?

MSIL is the name given to the intermediate language in .NET Framework Beta, 1.0 and 1.1. From version 2.0 onwards, the intermediate language is called CIL. We can say, MSIL is the old name. MSIL stands for Microsoft Intermediate Language. CIL stands for Common Intermediate Language. Its actually a low level human readable language implementation of CLI.

There is not much difference between the two. Compilers like vbc.exe and csc.exe compile the code into intermediate language. CIL is the name submitted by Microsoft to the European Computer Manufacturer's Association(ECMA) as a standard.