This is an interesting discovery I find when I was investigating a regression.
The following code is really Assembly.LoadFrom
AssemblyName assemName = new AssemblyName();
assemName.CodeBase = pathToAssembly;
resultAssembly = Assembly.Load(assemName);
It is the same as
resultAssembly = Assembly.LoadFrom(PathToAssembly);
Assembly.Load(AssemblyName) will first attempt to use the assembly name (name,version,culture,publickeytoken) to find the assembly. If that fails, and AssemblyName has a codebase set, CLR loader will attempt an Assembly.LoadFrom with the codebase.
In our example, since the name is empty, loader will directly try Assembly.LoadFrom on the codebase.