Size does matter

Size may not matter everywhere but when it comes to application file size, it does matter. I was working on a small encryption routine for my pet project. I decided to put this routine in an assembly so that it can be used for other application also. The assembly is to be written in C# language and development tool was Borland C# Builder. Simply, I created a project in C# Builder and added 2 .cs files, wrote a code and compiled it. The resulting assembly (.DLL) file was 7.5 KB big. Simple! Worked everything fine. Now something came to my mind and I fired up MS Visual Studio.NET. Created a project and added those 2 .cs files to it. Compiled it. Now what I saw was really surprising. This time assembly was about 20 KB big. I double checked everthing in both dev. tool for file count. Both projects had 2 .cs files. Now, can somebody tell me what is happening? Why VS.NET is producing bigger file than C# Builder? I am still confused !