Whereas we Orthodox see Catholicism and Protestantism as two sides of the same coin.
No, the decisions of the Council of Florence were not accepted by the Orthodox. There was no brief union.
The two sides of the same coin thing is often repeated by some Orthodox (though not necessarily by the Orthodox Christians I know in real life - some of whom agree that Catholicism and Orthodoxy ultimately share much more in common, though expressed differently), but it will never be accepted by any Catholic. Protestants, at least more traditional Reformation traditions, may use similar terminology, language, and frameworks in developing their theology, but their conclusions are radically different. The approach between Catholics and Protestants may be similar in many cases, but the CONCLUSIONS are at radical odds. The substance of what Catholics believe, when the philosophical framework is stripped away, is much closer to what the Orthodox believe in the vast majority of cases. The end result…
-Catholics and Orthodox believe Christ is truly present in the Eucharist. Most Protestants reject this.
-Catholics and Orthodox believe that we truly become like Christ through the sacraments (theosis / deification). Protestants tend to see “justification” as a mere declaration by God.
-Catholics and Orthodox venerate Mary and the saints and seek their intercession. Protestants reject this.
-Catholics and Orthodox believe that the bishops guide the Church as the successors of the apostles. Most Protestants reject this.
-Catholics and Orthodox believe that divine worship should be liturgical and rooted in tradition. Most Protestants reject this.
Take the specific example of the Eucharist. Do the Orthodox and Catholics have different understandings of the Eucharist? There are differences to be sure. But we both come to the same conclusion: HE IS PRESENT. We both bow down in adoration with this knowledge. Protestants look at the same Eucharist and say “its just bread”. To me the substance is that conclusion…not the theological or philosophical framework underlining the belief. I have friends and family who are Evangelical Protestants. I have friends and family who are Orthodox Christians. In face to face conversations of faith, I always find FAR more in common with the latter, and they agree with me. I don’t know why my experience of Orthodox Christians on the internet and those I have met in real life is so different on this particular point.
I could go on. What does it matter if the approach or philosophy is similar if the conclusions, what it ultimately points to, are radically different? Catholics and Orthodox approach theology differently but the end result is often much closer.