定语从句有没有逗号的区别是什么？

有逗号是非限定性定语从句，没逗号是限定性定语从句。

限定性定语从句只修饰前面的名词，但非限定性定语从句可以修饰整个句子。

例如：

He will wear no clothes which will distinguish him from his fellow men. 他将不会穿和同伴与众不同的衣服。
He will wear no clothes, which will distinguish him from his fellow men. 他将不穿衣服，这点让他和同伴与众不同。