Well basically in theory they are the same, the torah is essentially the old testament, but they differ slightly. Not least because of translation. Hebrew as a language doesn't translate well e.g. "thou shalt not murder" is 2 words in hebrew as opposed to 4 in english. Also many translations are innacurate, the wrong verb may be used, or in some cases the right verb may not even exist. There are other differences, such as those of interpretation, and the order of things, for example the ten commandments. However in judasim there are literally thousands of commentaries, on an A4 page you would have a business card sized area of torah and the rest would be commentary. People spend days arguing about the meaning of a single word, as a purely intellectual exercise. It's very different to christianity, everything is questioned and questioned again and no interpretation is infallible. It's hard to understand, if you wanna ask more add me.