Examples, please.
Show us what a Catholic considers a major differences in belief that are something that the Catholics thinks would or should or could affect one's salvation.
Is Baptism needed for salvation?
Can infants be baptized?
Is Jesus truly present in the Eucharistic bread (the Lutheran consubstantiation) or not?
And of course I can add the gulf between Evangelicals and the Liberal historical Mainline Protestants as well as the Arminianism vs. Calvinist debate.