Fundamental question - what is not and what is an attachment?

[I-Sampige, Srinivas]

After writing some code and after reading many articles on the web I am in a confused 
state. 

                I have a web service with the following method (I have registered the 
serializers and deserializers)
                                              public DataHandler getFile()
                                              {
                                                     ...
                                                     return dataHandler;
                                              }
                          how different is the above when compared to returning the 
file the following way? -
                                            
                                  public void getFile()
                                  {
                                      org.apache.axis.MessageContext messageContext =  
org.apache.axis.MessageContext.getCurrentContext();
                                      org.apache.axis.Message responseMessage = 
messageContext.getResponseMessage();

                                      
//responseMessage.getAttachmentsImpl().setSendType(org.apache.axis.attachments.Attachments.SEND_TYPE_DIME);

                                      responseMessage.addAttachmentPart(new 
AttachmentPart(dh));                                
                                  }     
                
                                            
                The reason I am asking the question is  because I thought that the 
second scenario was an attachment; the binary data being outside the soap message 
whereas in the first case ... the binary data was in the soap message thus being more 
inefficient. I compared the soap messages using tcpmon in all these approaches and 
they seemed similar in either approach. Looks like I have got into a state where 
everything is confused with so much information to make sense of so I  need SOMEBODY 
to HELP me straighten my understanding. Same goes for input of a file to a web 
service. What is different between  -

                                             public acceptFile(DataHander dh)
                                {
                                            }
                                                 
                                                     as compared to-
                                            public acceptFile()
                                            {
                                1. where I get the attachment out of the current 
message context here after I used the addAttachment() method on the client 
                                                    side before invoking this web 
service method.
                                            }
 

Thanks
Srinivas