Italy - Christmas Eve Night of "Seven Fishes" ( but its usually a lot more) presents opened two times once after midnight on christmas eve and then some smaller presents on January 7th on the epiphany. Christmas Day mass and spend the day with the family.
USA - Same as above just without gifts on the 7th
Decorations in italy Nativity (indoor usually under the tree) , lights outside minimal, alot of garland and a christmas tree
Decorations in the USA Nativity( outdoor and indoor), houses completely decorated, and Christmas tree
Always celebrated with extended family, close family friends as well. Example only my mothers side is here in USA and we have around 50 in house those days