I haven't seen both of them和I haven't seen either of them.有什么区别

I haven't seen both of them和I haven't seen either of them.有什么区别
I haven't seen both of them和I haven't seen either of them.有什么区别

I haven't seen both of them和I haven't seen either of them.有什么区别
前者表示两人并未全部见到,后者表示两人一个都未见到.像all ,both 等词的否定较特殊

一个是俩人没一起看到（both），一个是俩人一个也没看到（either）

1.不是两个都见过 2.两个一个都没见过

both of them侧重于两者都，而either of them为两者中的任何一个。以上两句是特殊语境中产生的特殊现象。