① temper可以指“脾气”、“性情”，mood则不可以：

This time, the policeman lost his temper.

这一次警察火了/发脾气了。

The boss is in a temper today.

老板今天脾气不好。

② temper指“心情”、“情绪”时，与mood同义：

That morning George was in a good mood/temper.

那天上午，乔治心情好。

但是bad mood与bad temper稍有区别，bad temper是指a persisting angry mood：

When he is in a bad temper, he gets angry easily. But when he is in a bad mood, he likes to sit alone.

当他脾气不好时，他很容易生气。但当他心情不好时，他喜欢独自坐着。

③ mood可以表示“有意/想要（做某事）”，temper则不可以：

At that time I was not in the mood for talking/to talk.

当时我没有心情/不想说话。