Αύριο είναι μία διαφορετική ημέρα
Αυγό είναι μία διαφορετική ημέρα
Αυγό = Egg Αυτό = It/This ;)
You cannot say 'Αυτό είναι μία διαφορετική ημέρα.' It is ungrammatical in Greek. Furthermore, you cannot replace 'today' with 'it/this/αυτό'.
Eh, i always make confusion between egg and tomorrow :P Edited.
Regarding your edit:
Αύριο = tomorrow. So, still not a good translation I'm afraid. Unless you're quoting Scarlett O'Hara, I suppose...
That :)
Does the word δια mean "light"?