Usually it is a matter of "distance"
This is my book = Αυτό είναι το βιβλίο μου (I have the book in my hands or it is somewhere close where one can see it)
I liked that book = Μου άρεσε εκείνο το βιβλίο (the book might be anywhere in the world)
Regarding it is and this is in Greek is the same as in English. The first is personal pronoun and the second is a demonstrative pronoun. In a written text maybe you don't always understand the difference but in a speech, yes.
Let me know if it makes sense.
Okay, so the way your use "this" and "that" is the same as English.
What I am asking is this:
Can Αντό here be translated as "This" or "That"? Or is it strictly "it"?
I may be asking this because Hebrew is my second language, and this/that/it often are all correct translations due to the lack of a neuter gender.
In English that has various explanations when it's used as a pronoun and one that I can find is: referring to a specific thing previously mentioned, known, or understood: that's a good idea | what are we going to do about that?
In Greek this phenomenon doesn't exist as we would use mainly αυτό: *αυτή είναι μια καλή ιδέα | τί θα κάνουμε γι'αυτό; *
Αυτό είναι ένα φόρεμα = It is / This is a dress
Εκείνο είναι ένα φόρεμα = That is a dress