Why some blend files looks different?

I do not understand why 10-12 blend files looks different than the other 100 that is in my blend file folder .
When I open Blender 2.71 -File- Open ( A) I see over 100 blend files lying there . Exactly as it should be .
But some looks different (B) I do not understand why. Do you, tell me why.
Thanks in advance.