who与that的区别
一、用who (whom) 而不用that的情形
(1) 在非限制性定语从句中的先行词指人时，只能用who (whom)。如：
My sister, who is studying abroad, sent me a beautiful present just before this Christmas. 我姐姐，她在国外学习，就在圣诞节前给我寄来了漂亮的礼物。
(2) 当定语从句对指人的先行词进行隔位修饰时，只能用who (whom)。如：
Do you know the girl in front of the blackboard who is speaking to the students? 你认识黑板前面正在给学生们讲话的那位女孩子吗？
(3) 当先行词为people和those时，只能用who (whom)。如：
Those who want to go there come here please. 那些想去那儿的人请来这边。
(4) 当先行词为one, ones, anyone, everyone, none, all(指人) 时，只能用who (whom)。如：
Anyone who is against us is our enemy. 任何反对我们的人就是我们的敌人。
(5) 先行词指人，而关系代词在从句中作主语时，一般多用who。如：
The man who came here yesterday said he would come again in a few days. 昨天来这儿的那个人说过几天他会再来。
(6) 在there be句型中名词的定语从句多用who (whom)。如：
There are students in our class who / whom you have met. 我们班有些学生你见过。
(7) 当句子中有两个指人的现行词分别带有两个定语从句时，若一个定语从句的引导词为that, 那么，另一个定语从句的引导词必定为who。如：
The boy that you met just now is Li Ming’s brother who just graduated from a university. 刚才你会到的那个男孩是李明的刚从大学毕业的弟弟。
二、用that 而不用who (whom)的情形
(1) 当先行词前面有形容词的最高级或序数词修饰时，引导词只能用that。如：
The tallest player that plays football for our team is from Shandong. 在为我们队踢足球的最高哪个运动员来自山东。
(2) 当先行词前面有only, some, any, no, every, little, few, much, all, very形容词修饰时，引导词只能用that。如：
He is the only student that said “no” to the teacher. 他是唯一的一个对老师说“不”的学生
(3) 当主句是以who开头的特殊疑问句时，引导词只能用that。如：
Who is woman that you talked with just now? 刚才跟你谈话的那位妇女是谁？
(4) the same as 与 the same that
the same as所引导定语从句的内容与先行词同类而不同物；the same that表示所引导的从句内容与先行词同类同物，即：同一事物。如：
She is wearing the same coat that I lost a few days ago. 她正穿着我几天前所丢失的上衣。(暗含：她偷了我的上衣)
She is wearing the same coat as I lost a few days ago. 她正穿着跟我几天前所丢失的上衣同样的上衣。(暗含：她所穿的上衣不是我所丢失的那一件)

that和who区别：
1. 两者均可指人，有时可互换(包括当先行词为 all, anyone, someone等，同时也包括先行词受the only等的修饰时)
2、当关系代词指人时，关系代词既可用who，也可以用that