在the pictures which were taken by me中,which were taken by me是一个定语修饰前面的pictures
the pictures taken by me 中,taken by me是过去分词短语作定语.
上面两种表达方法都是名词短语之间的互相转换（注意,不是句子,因为没有谓语）,名词中心语是pictures
但是如果改成the pictures were taken by me,就是一个句子了,the pictures是主语,were taken by me是谓语.希望能帮到你.