What is the difference (if any) between transition systems and finite automata? is there any difference between transition systems and finite automata? Is it that transition systems consist of both NFA (nondeterministic finite automata)
and DFA (deterministic finite automata)?
Yes, did you try wikipedia?

To quote the second paragraph [in transition systems]:


  
  The set of states is not necessarily finite, or even countable.
  The set of transitions is not necessarily finite, or even countable.
  No "start" state or "final" states are given.