score:9
Generally speaking there is no difference between sitting inside or outside, you are paying more just because you sit at a table.
This rule may be spelled differently on the price list, for example there is a single price and a "servizio al tavolo" extra.
In some places where you eat (restaurants, pizzerie, english style pubs) it may differ a bit... you are charged a "coperto" only if you eat and not if you drink only (coffee, soda, beer, wine or whathever).
The "coperto" is an extra charge for cutlery, bread and tablecloth.
I have no official source, I'm italian and lived in Italy for like 30 years.