I realize that I am a Roman Catholic on an Anglican thread and the last thing I wish to do is appear critical of your Communion (I often wish that many of the non-Catholics would extend the same consideration on Catholic threads), I am simply trying to understand why you left.
God Bless
I suppose the distinction is subtle, so I'll try to restate it:
1. I cannot support the doctrine that the Blessed Virgin, unique as she is in agreeing to bear the Son of God, was also conceived Immaculately. I believe this is not borne out in Scripture is violates both Tradition and theological sense.
That said, the BVM is the Theotokos, and as such is a great Saint in the Church Triumphant.
So, the two doctrines are separable: she who is the Theotokos is Venerable, but she is not also Immaculately Conceived.
2. The prior doctrine of Papal authority (pre-Vatican I) was that he was to be consulted on any proclamation of faith by any faith community. This meant he could object to any pronouncement of doctrinal authority. Hence, his Imprimitur was required to formally accept the doctrine of, for instance, hypostatic union of the Natures of Christ or to proscribe the doctrine of Monothelitism (one Will and Operation shared by the Natures of Christ).
Now, he may proclaim doctrines when speaking ex cathedra. This clearly adds to his authority. What would happen if a particular Pope proclaimed a doctrine a majority of faithful and informed Catholics instantly rejected is the concern here. It hasn't happened, but it could. Now it is true that even before Vatican I, councils could only be convened by the Pope, but this didn't matter as no one could assert doctrine without one. So we were doubly protected against the whim of innovation either by committee or in propria persona. Now, we have lost one of those protections.
Surely, stated thus, the difference between the two formulations must be clear.
3. The Treasury of the Saints underlay the practice of indulgences, which continues (I have in hand, for instance, a card which tells me that if I repeat the prayer every day for a month I will be granted 3 years indulgence). This implies that there could be a surplus of grace afforded by the prayers of the saints which could then be applied to the punishment justly due of other saints, hence indulgence. This was, if memory serve, the theological underpinning of the English Reformation, alongside the more mundane issue of Henry VIII's domestic problems and the certainly more important issue of ecclesiastical control in England.
Rather a longish discussion there, and for which my apologies, but the point is that I reject that there is a surplus of grace that one saint can have transferred to another. I emphatically support the concept of intercessional prayer, however, where one saint pleads for God to pour his grace on someone else. However, the effect is to intend to intensify the person's response to the grace afforded, not apply credits against whatever penal or purgative judgment he/she may have incurred. The best that can be gained is that the person interceded for has now more spiritual strength, fortitude and virtue to walk the pilgrimage, including whatever durance in Purgatory is required. No durance is remitted, however.
Does this help? And I should also note that I did not go straight from Roman Catholicism to Anglicanism. I went out of the Church at about the age of 13. When I came back 12 years later it was to an Episcopal Church. I arrived just in time to experience the bust-up.
In Christ,
Deacon Paul+