Christmas is to celebrate Christ's birthday. It's a day when Jesus Christ was born. We celebrtate because he is the messiah that came to save us all from our sin. Which he then died on the cross and rose again three days later. But that has to do with Easter. You get presents because it is a day of giving to one another. Which means there is no Santa.
Santa Claus is the legendary patron- saint of children, an imaginary being who is thought to bring presents to children at Christmas.They just did some thing for little kids so they have some fanasty in their mind.
Historically, it's 'winter festival'. Christmas is just a couple days following the 'shortest day' for the northern Hemisphere. That means that the north poll of the earth's axis is pointing away from the Sun.