Catholics and Protestants are both Christians, Catholicism is pretty unified in doctrine, and Protestants are a large group of very diverse denominations of Christianity. When I was forced to go to church, my pastor would often joke about Baptists forming new denominations over differing opinions on drape colors. Outside of those two groups, there are tons of other flavors of Christianity. Off the top of my head you’ve got Mormons, Greek Orthodox, Eastern Orthodox, jehovas witnesses, and Oriental Orthodox