,These two words can be used both as preposions and conjuncrtions.They mean exactly the same.Till is informal British English(in American English,till is the preferred informal spelling).上面的英语你能看懂吗？也就是说：两个没有区别，中国老师是最爱把简单问题复杂化，till非正式，untill正式一点。 孙老师