So Catholicism is a different religion than Christianity? Also, does the same apply to Eastern Orthodox Church and the likes as well?
Roman Catholics, Protestants, Eastern and Russian Orthodox Christians all have the same basic beliefs. One of the oldest statments of faith is the Nicene Creed, which was written in the fourth century and describes Christian belief about God the Father, Son and Holy Spirit. All major branches of the church agree on this. The word "catholic" in the last part means "universal", not "Roman Catholic".
There are lots of practices and smaller differences and degrees of emphasis that divide Christian churches: the authority of the Pope, the role of liturgy in worship, the status of Mary the mother of Jesus, and so on. I know that Buddhism has many different branches too.
Here's the Nicene Creed
We believe in one God,
the Father, the Almighty,
maker of heaven and earth,
of all that is, seen and unseen.
We believe in one Lord, Jesus Christ,
the only Son of God,
eternally begotten of the Father,
God from God, Light from Light,
true God from true God,
begotten, not made,
of one Being with the Father.
Through him all things were made.
For us and for our salvation
he came down from heaven:
by the power of the Holy Spirit
he became incarnate from the Virgin Mary,
and was made man.
For our sake he was crucified under Pontius Pilate;
he suffered death and was buried.
On the third day he rose again
in accordance with the Scriptures;
he ascended into heaven
and is seated at the right hand of the Father.
He will come again in glory to judge the living and the dead,
and his kingdom will have no end.
We believe in the Holy Spirit, the Lord, the giver of life,
who proceeds from the Father and the Son.
With the Father and the Son he is worshiped and glorified.
He has spoken through the Prophets.
We believe in one holy catholic and apostolic Church.
We acknowledge one baptism for the forgiveness of sins.
We look for the resurrection of the dead,
and the life of the world to come. Amen.
