What is the difference between denominations in churches?

I don't know the differences but some are cultural reasons and because of the religious scholars who formed these churches. They learned the Bible interpreted it and chose to focus on particular teachings of the Bible. Some follow only the new testament, some follow the whole thing and some follow the old testament. Some talk about certain books of the Bible or they use certain Bibles in their churches. Its all confusing to me too. Look it up. My family is christian but I am not. I understand it is confusing.