Ⅰ. be sure 指某人对某事或对某种情况有把握，常译为：“确信”；

make sure 指“务必、务请、确保”将某事弄清楚。如：

① I am sure that he is honest. 我相信他是诚实的。

② I have made sure that he is honest. 我已了解清楚他是诚实的。

Ⅱ. 二者后面均可接of 或about 引出的短语。如：

① I am sure of success

= I am sure that I will succeed. 我深信会成功。

② Will you make sure of his return?

= Will you make sure that he returned? 请你查明他是否真的回来了。好吗？

Ⅲ. make sure 后面的that 从句一般不用或很少用将来时；

be sure 后面的that从句则可用将来时。如：

① Make sure that you come here before five. 你一定要在5点前来。

② I am sure that he will come. 我相信他一定会来的。

Ⅳ. 两者后面接不定式，均表示“一定要做某事”，但make sure 通常只用于祈使句；

而be sure 则不受限制。如：

① Make sure to come to party on time. 一定要准时来参加晚会。

② He is sure to call you up. 他准会给你打电话的。