A typicial Protestant would say that sinners are saved by grace alone, through faith alone, in Christ alone. A typical Roman Catholic would deny this. To say that the life and death of Jesus Christ makes salvation possible is true, as far as it goes. But such a statement does not tell us what we need to know, namely, what must we do to be saved?
I suspect this confusion stems from that for whatever reasons long ago lost in history, the Roman Catholic Church tended to stress "good works" over acceptance of Christ, perhaps making it seem being a "good" person could by itself earn one Eternal Salvation.
It wasn't the government building all of those hospitals, colleges, orphanages, hospices, &c., &c., &c., during the Dark and Middle Ages, and clear into circa the middle of the 19th century.
And so it may have been easy to construe Catholic theology as stressing charity over faith, when it comes to Eternal Salvation.
But the real deal is, going "good works" is meant to enrich one in this time and place, this life, while acceptance of Jesus Christ is meant to earn one Eternal Salvation.
Another important difference: What is the final authority for the Christian? Protestants say the Bible is the infallible, authoritative, final and sufficient word of God. The Roman Catholic Church says that, while the Bible is inspired, we should have an implicit faith in the official Church of which the pope is the head and teacher.
The Bible of course is the final authority.
The Bible however is a very complex thing, and most humans (and all primitives) have not the intellectual and spiritual means to understand it fully, even if one does nothing all his life but read and attempt to interpret the Bible.
For Roman Catholics, the role of the Church is as "teacher" of the Bible.
One should not think too lightly of Popes and Cardinals; even during the most depraved days of Roman Catholicism, these tended to be guys well educated, with extensive knowledge of human languages live and extinct, with ample access to voluminous material. These were, and are, not ordinary people.
This is the same thing as when I was 15 years old, learning how to drive, and the parents instructed "don't drink and drive," advice which I, happily, followed. The parents knew, and understood, a great many things I didn't, and so it was just best to take their word.