The major difference was that new slavery entails the slaves been treated harshly and destined for exhausting labor while the European Slavery were mainly for domestic labor.
<h3>What was the earlier forms of European slavery?</h3>
These European slavery were used for domestic servitude rather than for harsh laborsuch as Black labor in the U.S.
Therefore, the major difference between the two era of slavery was that new slavery was a high-volume business where theslaves were treated harshly and for exhausting labor.
The answer is because United States was concerned about crimes against humanity being committed there. They were also concerned that Spain would have power so close to US territory.