provided(或providing)是连词,supposing(或suppose)也可作连词,英文意思都是if,但是实际上两者含义不同.provided(或providing)用来表示条件,supposing(或suppose)用来表示假设.
supposing(或suppose)的含义是:What would/will hanppen if...,所以常用在问句中.
用法上也有区别,provided(或providing)后面可加that,也可以不加,意思还是一样,supposing(或suppose)后面不加that.