so tired与too tired

so tired: 好累

The boy was so tired that he fell asleep immediately.

这男孩太累了，马上就睡着了。

I couldn't concentrate, presumably because I was so tired.

我的精神集中不起来，大概是太累了吧。

too tired:

太累了

She had to admit that she was too tired.

她不得不承认她太累了。

I'm too tired even to think.

我累得连想也不愿意想。