State Transition Diagrams for XOR I have found two different versions for State Transition Diagrams for XOR.

I'm confused as to why one has 2 states and the other has 3. What are the implied states in each please?

Are they both functionally equivalent? Are there situations where one is more appropriate than the other?
On the left you have a DFA that accepts the language of all strings over $\{0,1\}$ in which the XOR equals 1.

On the right you have a Mealy machine in which each output is the XOR of the two recent inputs (the first output is always zero).