A change of religion took place subsequent to Vatican II wherein the post-Vatican II religion bears no resemblance at all to the pre-Vatican II religion.
It was, in effect, a drastic change of religion.
Despite the postings of well meaning neo-catholics who have attempted to fuse the pre- and post Vatican II church (mainly by cutting and pasting documents that nobody reads or obeys) the basic and huge differences remain.
Since Vatican II offered no new dogma there is nothing for the amateur theologians to discuss, there's no dogmatically defined differences. What there is, is a huge difference in praxis, culture, a new calendar, a new Bible translation (the New American Bible), a new constantly-evolving liturgy.
I go to both the Tridentine Mass and the Novus Ordo and I cannot resolve the two.