This is a short test of comparing the public API in two .NET binaries. There isn't any special comparison being done beyond determining whether or not the public APIs match perfectly.
To determine whether or not the two APIs match, build the .cs files like so:
csc /out:Lib1.dll /target:library 10_Lib1.cs
csc /out:Lib2.dll /target:library 20_Lib2.cs