.NET assembly and PE file区别

PE section	Contents of PE section
PE header	The index of the PE file's main sections and the address of the entry point. The runtime uses this information to identify the file as a PE file and to determine where execution starts when loading the program into memory.
MSIL instructions	The Microsoft intermediate language instructions (MSIL) that make up your code. Many MSIL instructions are accompanied by metadata tokens.
Metadata	Metadata tables and heaps. The runtime uses this section to record information about every type and member in your code. This section also includes custom attributes and security information.

The Portable Executable (PE) format is a file format for executables, object code, and DLLs, used in 32-bit and 64-bit versions of Windows operating systems.

http://msdn.microsoft.com/en-us/library/8dkk3ek4.aspx
http://msdn.microsoft.com/en-us/library/zst29sk2.aspx