"But Mary did not receive anything different that the sanctifying grace we receive."
This does not seem to mesh with the text of the Papal encyclical regarding the Immaculate Conception, which, as I understand it, does not reflect just an absence of the spot and stain of original sin, but also filling her with a plenitude of graces from the moment of her conception -- such that she has excess grace and merit that can be applied to others. I haven't the time right now to look it up, but I think you know the passages I refer to.
I do not believe that Catholicism teaches that at the moment of baptism, that one is automatically filled with grace in this way.
On the other hand, the Orthodox belief is that Mary reached a state of theosis that can and never will be attained by anyone else, since for 9 months her blood mingled with that of Christ, and her body enveloped the uncircumscriable God. This is a degree of union that left her changed forever, and is impossible for anyone else ever to experience. I would imagine that we would agree on this point -- but would disagree on the starting point.
That is an interesting comment, for it was my impression that the flesh and blood of Christ was not His but Mary's. Else, whence came His own flesh? If He were to be indeed covered by pre-fall flesh, then it would make sense what the Latins believe -- Mary would have to be the pre-Fall Second Eve or else her own flesh would be a post-Fall flesh.
But I will take this a step farther: first Adam did not have a mother. Why would the second Adam need one? So that He could be from the line of David? But I thought the lineage in Judaism was passed via the male line, so how could Christ claim Davidian lineage through His Mother?
Besides, Christ could not have been genetically the same as we are. His humanity comes from His Mother alone. Not exactly like the first Adam, is it?
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On the other hand, the Orthodox belief is that Mary reached a state of theosis that can and never will be attained by anyone else
First, and as an aside to any Protestnat reading this, these are the superabundant merits of Christ that she dispenses, -- none of her own, as she remains fully human, -- in fact, more human than we are. There may be a difference indeed because as I understand the Orthodox Church teaches that the grace flows equally to all, whichis not the Catholic teaching in general (see the Parable of the Talents why).
The second part of your post shows that despite the great differences in theological method, we arrive in the same place insofar as our needs in praxis are concerned. Surely you don't think it ill-advised to ask for Mary's prayers, especially when in the hour of our death our own pious disposition might be not at its height.