Eastern Christianity confuses some very faithful Christians, Catholics and Orthodox people especially.
I recommend this brief essay by Jesuit Father Steven Hawkes-Teeples, “Eastern Christians and Their Churches” (Catholic Information Service, Knights of Columbus)
From the Catholic perspective, here are some videos to watch:
Eastern Catholic Church – An Introduction by Father Thomas Loya
Eastern Catholic Theology – Part I by Abbot Nicholas of Holy Resurrection Monastery
Eastern Catholic Theology – Part II by Abbot Nicholas of Holy Resurrection Monastery