The Spaghetti westerns films differ a lot than the Westerns that are made in the US by the US directors. I guess the major difference in them is the Violence. Spaghetti westerns are way more violent than the American Westerns.
Also, one of the movies shows reversal of roles. In the movie Navajo Joe we see that he (a native Indian) has been portrayed as the hero and the American white men are the bad guys, we see how Joe saves the entire village. In the regular Western, the Natives were always shown as the inferior class and the White American as the good guys.
In the movie The Good, The Bad, and The Ugly, we see that all the three main characters are continuously willing to kill each other. The gold makes them all the more violent. They constantly make promises and break them. It’s no big deal for them to break their word. All they cared was about themselves and how they could make more money. In the American Western we never see an Alpha male turning back from his word. Once he had said anything, that was engraved in the rocks. No one could change that.
We see how the perspective of the International Audience is completely different from the Americans. They feel that the Americans were not to be relied on nor were they really good people who cared for the society. They were violent, and very destructive. The natives who were thought of the Salvages in the American society were actually the real Hero’s in the mind of the International people.