Well, by the 15th century (the 1400s), the Europeans were already in the Iron age two levels higher than the stone age that the Americans were still in. They had given up human sacrifices, developed a writing system for their languages and were well on their way to scientific studies.
In the Americans, the only mental working was a bit of gold and silver, Human sacrifices were still the "norm" and a few priests could read the pictograph "writing" that they had developed. Large empires such as the Incas and Aztecs enslaved total and complete people after capturing them.