IF A XOR B, THEN A OR B
Proof: If A XOR B, then exactly one of A and B must be True. Ergo, A OR B must be True.
(FWIW, The converse fails when A=B=True.)
Therefore, if "today xor tomorrow" is true, then "today or tomorrow" is also true. "today or tomorrow" may admit more states, but that just means an easier question was asked than could have been asked. For example, if I asked, "are there at least 14 days in this month", the answer would be yes, despite the fact that I could ask if there are at least 28 days and stil have a response of yes.