They ,most of the time,I may say,are the same. A warning:you can say:"因为..........，所以........"，and you can say:"......，所以....." you cannot ,however, say:"因为......，因此........"。 The correct one is:"......，因此....." eg. I caught a cold ,so i cant go to school. 因为我感冒了，所以不能去上学 我感冒了，所以不能去上学。 我感冒了，因此不能去上学。 I‘ve said that, you cannot say:"因为 我感冒了，因此我不能去上学"

因此 thus ,consequently ,as a result 他迷恋于玩游戏，因此无心学习，成绩下降 Ta milian yu wan youxi, YINCI wuxin xuexi, chengji xiaxiang. He is obsessed with playing games, SO he's not interested in studying and his achievements have dropped off. In the following example ,it means 'as a result ' and would be expressed in English as 'due to': 由于引进了先进技术，生产效率因此大大提高 Youyu yinjinle xianjin jishu, shengchan xiaolu YINCI dada tigao. The production rate has increased hugely due to imported advanced technology.

they have a little diffience,因此 usually use in composition.It‘s a offical word.when we chat,we never use it .所以 is a useful word.we use it everywhere.

所以 therefore, so ,as a result 路上堵车，所以我迟到了。 Luchang duche, SUOYI wo chidao le. There was a lot of traffic, so I am late. 她之所以成功，是因为坚持不懈。 Ta zhi SUOYI chenggon, shi yinwei jianchibuxie. The reason for her success, is her unremitting effort. As you see they have both almost the same sense ,but they won't be always interchangeable ,each of them will be suitable for a certain sentence strucutre and context.

“因为”不与“因此”连用，一般用“所以”， “由于”可以与“因此”连用，不般不接“所以”。