so as(not)to 与 in order(not)to 的区别

so as(not)to 与 in order(not)to 的区别
这两个短语在下面两个句子中的用法有区别吗?
I took the doctor's advice in order not to continue taking drugs.
I refused to take the drug so as not to become addicted.
他们之间好像有细微差别。有5道选择题让用这两个短语填空。下面的是其中之一：She stopped smoking ________ be fit.麻烦各位多指教。