What is the difference between FA , TG , GTG. ?

i have no idea 

thanks

• 
  

  n Finite Automata transitions are marked with single letter of alphabet. In Transition Graph, they can be marked with letters or strings (combination of letters).

  
  


• 
  

  In Finite Automata states transition are shown for all letters of given alphabet. In Transition Graph, it does not necessarily shows transition for all letters.

  
  


• 
  

  Strings transitions can be showed with TGs but impossible with FAs.

  
  


• 
  

  In GTG transition edges are labelled about RE but in TG edges are labeled with strings.

  
  

This is not perfect answer