Hi,
May I know what are the differences between Catholicism and Christianity?
Both worship God and Jesus Christ right?
I'm a non believer initially but are having more interest now as I am starting to believe in..
The full complete answer can fill a whole book. But the nutshell answer is this: The difference between Catholicism and Protestantism (Not Christianity which is a local Singaporean misconception as Catholics are Christian too) is that Catholics have chosen to remain faithful to the original teachings that have been passed down for close to 2000 years now, while Non-Catholics on the other hand have abandoned 2000 years of Christian theology and re-invented their own version of Christianity based upon their reading and understanding of the Bible.
If you want more information look up an encyclopedia or a good history book on the protestant reformation.
Here is a link to the branches of Christianity.
http://en.wikipedia.org/wiki/Image:ChristianityBranches.svg
Hope it helps. Wikipedia has a good article
http://en.wikipedia.org/wiki/Christianity
and is pretty neutral and looks at the Christianity from a historical perspective.
Try not to look for sources that are written by Protestants or Catholics. Look for sources that are written from a historical perspective to avoid biasness.
I wish you all the best in your search for the Truth.