Diff between Normal Postback by a button Click and a postback using __doPostBack in javascript ?

Question

Question is the title itself.

 __doPostBack('<%=btnABC.UniqueID %>', '') and 

  onClick="Button1_Click" 

Answer 1

you could refer to the following threads which discuss same: What is the difference between client browser's submit mechanism and the ASP.NET postback mechanism? &

Button click/page submit from JavaScript