Assmbly.GetTypes()

represents type declarations: class types, interface types,array types,value types, enumeration types,type parameters,generic type definitions,and open or closed constructed generic types.<from msdn>

type.IsAssignableFrom
Determines whether an instance of the current type can be assigned from an instance of the specified type. 
example:
int i =0;   i.GetType() is Int32.
int[] array1 = new int[2];  array1.GetType is Int32[]
so i.GetType().IsAssignableFrom(array1.GetType())  returns " False"

IDisposable  interface System.IDisposable
Defines a method to release allocated unmanaged resource.