jquery Object data Cache principle and Jquery.data explanation

Online there's a lot to teach you how to use Jquery.data (..) To implement the data cache, but there are two users who often use data ([Key],[value]) and Jquery.data (Element,[key],[value]) There are few articles that tell the difference between them, so I used the research to share with you.
$ ("") The difference between data ([Key],[value]) and Jquery.data (Element,[key],[value])
Both of these functions are used to store data on the element as well as the usual data cache, all return jquery object, when I used it in both of them really scare me, the difference can be big, really do not know, a scare jump. Look at the example first, and then according to the source code analysis. JS code:  <div id= "test2"  onclick= "Test ()" >test2</div>              <div id= "ABC3"  onclick= "Test ()" >test3</div>              <div id= "Test"  onclick= " Test () ">test</div>             <p  Id= "TTT" >aaaa</p>       <script>          $ (document). Ready (function () {           $ (" #test "). Click (function () {           alert (" JQUERY ");                 var e=$ ("div");// Two jquery objects     &nbs definedp;   var w=$ ("div");//e is not equal to W.            //First uses the data ([Key],[value]) usage.          $ (E). Data ("A", "AAAA"),/////Save Key on E and W,          $ (W). Data ("A", "wwww");//  see if it will overwrite the previous one, although it is stored on a different object.          alert ($ (e). Data ("a");//Have you guessed the answer, the output is wwww; it's a little unexpected.          alert (e===w)//false          alert ($ (w). Data ("a"));//This is wwww;             // Use Jquery.data (Element,[key],[value]) to store data.          $.data (E, "B", "CCCC");//Save key-like data on E and W,          $.data (W, "B", "dddd");//  see if it will overwrite the front, although it is saved on a different object.          alert ($.data (E, "B"));//Should you be able to guess the answer, output cccc       &nbsP;  alert ($.data (W, "B"));//This output dddd                    });        });   </script >  

See the above example is not found that data ([Key],[value]) and Jquery.data (Element,[key],[value]) Two is not the same, right. Is there any relationship between them? How does data ([Key],[value]) overwrite the same value as the previous key?
Jquery.data (Element,[key],[value]) does not cause an overlay as long as it is bound to a different object. Is that so? Let's take a look at their source code.
See Jquery.data (Element,[key],[value]) source code first. JS Code:   jquery.extend ({       cache: {},           // Please use with caution       uuid:  0,          // unique for each copy of  jQuery on the page       // non-digits removed  to match rinlinejQuery       expando:  "JQuery"  +  (  jquery.fn.jquery + math.random ()  ). Replace ( /\D/g,  " ),           ....       data: function ( elem,  name, data, pvt /* internal use only */ )  {       //  whether data can be appended, not directly back to            if  ( !jquery.acceptdata ( elem )  )  {                return;            }              var privatecache,  thisCache, ret,                Jquery.expando This is a unique string that is generated when the jquery object is created.                internalKey =  jquery.expando,               getbyname  = typeof name ===  "string",                   //  must distinguish between the handling of DOM elements and JS objects, because ie6-7 cannot garbage-reclaim objects that are referenced across DOM objects and JS objects                 isnode = elem.nodetype,                    //  if it is a DOM element, use the global jquery.cache                  //  if it is a JS object, attach directly to the object                 cache = isNode ? jQuery.cache :  elem,                  //  Only defining an id for js objects if its cache already  exists allows               //  the code to shortcut on the same path as a DOM  node with no cache                id = isnode ? elem[ internalkey ] : elem[ internalkey ] & & internalKey,                isevents = name ===  "Events";                //  avoid doing more without having to work when trying to get data on an object that doesn't have any data           //  Object does not have any data, direct return       &n