“More explicit, but not greatly different from what the US constitution and the common law indicated”
Greatly different in one way. Under the Confederate Constitution, slavery was mandated in all Confederate states and territories. In the United States Constitution, slavery is not mandated. A state could outlaw the practice if they so choose. By 1860 15 states had made the practice of chattel slavery illegal, and it was illegal in all Territories of the United States.
That's a matter of interpretation. Again, the Confederate constitution was very explicit about it, but the US Constitution can be interpreted to mean the same thing.
George Washington kept slaves in Pennsylvania after that state had passed a law making it illegal.
I think efforts to bar slavery in states run afoul of Article IV, which guarantees all the privileges and immunities of the citizens of the various states.
How can you have a system in which slaves are recognized as property by the entire Union, but then not allowed to be in some states, but allowed to be in others? This seems like a clear infringement of the immunities and privileges clause.
Other people felt states had a right to ban slavery within their borders and saw no conflict with the rights guaranteed to the citizens of other states.
Which view is correct is not completely clear. I think the US constitution can easily be interpreted to mean the same thing as this aspect of the Confederate constitution, but the Confederate constitution leaves no doubt at all.
That's what I mean when I say it is clearer on the point.