請講出呢兩個字既分別

冇分別
可以互通使用

assure - 保証 , 使.....確信
I assure you I did not take away your book .
He assures me everything will be OK
ensure - 保証 , 確保
His new book ensures his success .Please ensure all lights are
switched off when you leave .
兩字意思十分接近,但並不百分百相同 .
(http://www.rthk.org.hk/elearning/yangtl/mailbox_p36.htm)

2008-04-23 04:56:25 補充：
To “assure” a person of something is to make him or her confident of it. According to Associated Press style, to “ensure” that something happens is to make certain that it does, and to “insure” is to issue an insurance policy.

ensure
vt.
1. 保證;擔保[O9][+that][+v-ing]
I can't ensure his being on time.
我不能保證他的準時。
I can't ensure that he will be there on time.
我不能擔保他會及時到那兒。
This medicine will ensure you a good night's sleep.
這藥將保證你一晚睡眠良好。
2. 使安全,保護[Q][(+from/against)]
These are safety devices to ensure workers against accidents.
這些安全設施是為了保護工人不出事故。



assure
vt.
1. 向...保證,擔保[(+of)][O5]
I can assure you of the reliability of the information.
我向你保證這消息可靠。
The captain of the ship assured the passengers that there was no danger.
船長向乘客保證沒有危險。
2. 使確信,使放心[(+of)][O5]
We assured our clients of an enjoyable holiday.
我們使遊客確信准能過一個愉快的假期。
3. (後接oneself)使弄清楚,使確定[O5]
They assured themselves that the bridge was safe before crossing it.
他們直到弄清楚那座橋確實安全後才通過。
4. 確保,保障
Her future was assured.
她的未來是有保障的。
5. 保證給予[O1]

assure 既意思係「向sb 保證」
通常後面都會加pronouns
另外通常都係用響passive voice

ensure 則唔會加pronouns
而且係active voice

....講解得唔係好details...你去yahoo 字典,比較下d例子, 可能會清楚d