I know the story about siddhartha. But is gautama buddha the same person
Or a different person than Siddhartha

The following site says he is the same person: The Buddhist World: Gautama Buddha (http://www.buddhanet.net/e-learning/buddhistworld/buddha.htm)
So does this site: Gautama Buddha - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Gautama_Buddha)
As well as this site: Siddhartha Gautama (http://webspace.ship.edu/cgboer/siddhartha.html) and this:
An Introduction to Buddhism (http://webspace.ship.edu/cgboer/buddhaintro.html)