Game VS Opening VS Gambit VS Defense

I'm new at all this, so this is a terminology question. There is the Italian GAME. There is the Giuoco Piano OPENING. There is Evans GAMBIT. And there is the Hungarian DEFENCE. All of these are biased off of the Italian GAME, or so I think, I could be wrong. This is one of those things I didn't pick up on in the first couple of months.  Am I right to say, 'This is how things are broken up'? "Games" have "Openings". "Openings" have "Gambits" and "Defenses". "Gambits" can be White or Black moves, and "Defenses" are only Black. I am asking this to clarify things. Am I studding the Italian Game when I look at the Giuoco Piano OPENING, is that a line in the Italian GAME or is it its own separate thing? If they all are under the Italian GAME, is there some kind of list? It would be nice to know if this OPENING goes with this GAME. Or if, for example, the Queen's GAMBIT goes with this "X" OPENING. This is a little confusing for a new guy. I get that there is exceptions for every rule, ESPECIALLY IN CHESS. And I am sure there are times when things fall outside of the 'Normal'.  But in general, is this how it works? Is there a way of knowing 'This OPENING goes with this GAME'? How do I clear up this confusion? How do I know the difference between these 4 words?

i have no clue good sir