Exactly what is the difference between Finite Automata and Transition Graphs?
Your nomenclature is highly nonstandard. It seems that "finite automata" are what are usually known as DFAs, whereas "transition graphs" are a special case of GNFAs in which the only regular expressions allowed are words; alternatively, they are like $\epsilon$-NFAs, only transitions can be marked by arbitrary words (rather than just words of length at most 1).

There are two differences between your FAs and your TGs:


FAs are deterministic: at each point in time, there is exactly one choice of which state to go to next. There is no such restriction on TGs. Moreover, whereas FAs have a unique initial state, TGs have an arbitrary number of initial states.
Transitions in FAs are labeled by symbols. In contrast, transitions in TGs are labeled by words.


These are exactly the differences that you listed.