区别：
一、意义不同
1、as to提及某人或事，不涉及讲话人的态度。引出做事的依据：“按照”、“根据”。
As to your ability to overfulfil the target，Ineverhad the slightest doubt．
2、as for用以转换话题,与前文形成对照，译作“至于”。用以表现态度,带有贬义。译作汉语的“至于……”。
You have a bed；as for him，he'll have to sleep on the floor．
二、搭配不同
1、as to用以重提旧事，asto引出的内容都是前文曾经提到过的或者谈话对方都有所了解的，表示“说到”之义。
As to doing that，I haven't decided yet．
2、as for通常总是放在句首，对于突然想到的事情或临时提起的问题，以使用asfor为宜，并可引导动名词短语。
As for that，we shall see later．至于那件事，往后我们便见分晓了。
扩展资料
例句
1、This gave me a clue as to the source of the problem.
这件事给我提供了找出问题根源的线索。
2、The dietitian was helpful, making suggestions as to how I could improve my diet
这位营养学家就如何改善饮食给我提出了些建议，对我很有帮助。
3、No one has come up with a definitive answer as to why this should be so
对于为什么应该是这样，还没有人想出最终确定的答案。
4、As for Laura and me, the colour of our skin has never mattered
至于我和劳拉，肤色根本不是问题。
5、As for her engagement with Adam, I would say the portents are gloomy.
至于她和亚当的婚约，我看兆头不妙。
参考资料来源：百度百科：as