one of them引导的是并列分句.即分句＋one of them分句
这里分句和one of them分句要用分号连接或者在one of them前面加连词and/but等.
one of which引导的是定语从句.即主句＋one of which从句
这里主句和one of which从句直接直接可以用逗号连接(非限制性定语从句),或者根本不用逗号(限制性定语从句).
There are many books,and one of them is mine.
=There are many books; one of them is mine.（注意这里是分号）
=There are many books,one of which is mine.
欢迎探讨词法语法问题.