同学你好，该知识点来自沪江网校《【Uni智能】雅思6.5分一站式VIP-初级起点【全额奖学金签约班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
没有区别，for example更正式，都可以加逗号。
There are a number of improvements; for instance, both mouse buttons can now be used.
They will be concerned to do the right thing — to dress properly, for instance.
他们需要注意行为是否恰当——比如说，穿着得体。
Let us suppose, for example, that you are married with two children.
比方说，我们假设你成家了，还有两个孩子。
Many factors are important, for example class, gender, age and ethnicity.
许多因素都很重要，如阶级、性别、年龄及民族。

祝同学学习进步~