Well, being relatively new to this scene I have been learning a whole bunch of new acronyms (DATY, digits, MSOG, etc.).   
  
There are two that I am unclear as to what the difference is between them.  They are GFE and PSE -  the line seems somewhat blurred.  I have read a few points of view and they all differ.  I would like to have some idea of what to expect (and not expect) from a service provider who advertises one of these services. 
  
Any info would be welcome.