former是以前或者前者的意思，而latter则是后来的意思，区别可以从以下例子看出：

How many girlfriend have you had, the one we saw yesterday was your former one, the one I have met today you said she is latter one. 你有过几个女朋友？昨天我们看到的是你的前一个，我今天遇到的你说她是后来的一个。