Is subcbrionic bleeding in early pregnancy anotber term for spotting?

No exactly: Subchorionic bleeding is bleeding within the folds of the chorion (the outer fetal membrane, next to the placenta) or within the layers of the placenta itself. This bleeding can cause the placenta to separate from the uterine wall if it forms a big clot under the placenta. Frequently, though, it causes spotting for a few weeks and then goes away. Best wishes!