activex dll vs .net dll in sidebar gadgets

Why can I load a .net assembly in an IExplorer browser as per this example (html page and dll are in the same dir):

<OBJECT id="myControl1" name="myControl1" classid="ActiveXDotNet.dll#ActiveXDotNet.myControl" width=288 height=72>
</OBJECT>

that's from this sample:

http://www.c-sharpcorner.com/UploadFile/dsandor/ActiveXInNet11102005040748AM/ActiveXInNet.aspx ArticleID=99d9681d-84de-4d64-9c85-9ae9c15a4ee7

but for a sidebar gadget I have to have to assign a guid to my class, make it com visible, write to the registry and all that as shown here:

http://blogs.msdn.com/jaimer/archive/2006/10/02/writing-a-.net-activex-control-for-your-sidebar-gadget_2E002E00_.aspx

I thought sidebar gadgets were something like mini docked html apps. It would sure be nice to "call your .NET assembly very similar to an ActiveX control; however there is no GUID, and no .OCX file. Your CLASSID is now the path to your DLL and the Namespace.Classname identifier."

Last quote is from the first sample.

Thanks,

DanT