will与begoingto有何区别

will和be going to 都表示“将要（做某事）”，二者的区别在于：
"will" 表示在说话的时候才作出决定，
而"be going to"表示在说话前就已经计划好了

用于条件句时， be going to 表将来
will 表意愿
If you are going to make a journey, you'd better get ready for it as soon as possible.
Now if you will take off your clothes, we will fit the new clothes on you in front of the mirror.