You can use MethodBase.GetMethodBody
followed by MethodBody.GetILAsByteArray
in order to get the MSIL for the method body as an array of bytes. As the second link notes, however,
Parsing method bodies requires a thorough understanding of metadata and MSIL instruction formats. Information can be found in the Common Language Infrastructure (CLI) documentation, especially "Partition II: Metadata Definition and Semantics" and "Partition III: CIL Instruction Set". The documentation is available online; see ECMA C# and Common Language Infrastructure Standards on MSDN and Standard ECMA-335 - Common Language Infrastructure (CLI) on the Ecma International Web site.
Even if the two methods have the same MSIL, they did not necessarily originate with the same C# source code. You could attempt to decompile the MSIL into C# source code using something like Mono.Cecil, DelegateDecompiler, or ICSharpCode.Decompiler, but I would not recommend going down that road and instead suggest reconsidering your approach.