Ok, Early Binding vs. Late Binding...
VB Code:
  1. 'Early Binding
  2. 'Add a reference to MS Excel xx.0 Object Library
  3. Private moApp As Excel.Application
  4.  
  5. 'Late Binding
  6. 'No reference added to Excel at all
  7. Private moApp As Object
Early binding locks in your reference to that version of Excel. Late binding does not. It only binds to the version that is available on the system.

With Early binding you get the intellisense popups showing the functions, methods, and properties of your object variable. Late binding does not support any intellisense since it doesnt know what it is until runtime.