Tired（1. In need of sleep or rest; weary; 2. Bored or impatient with; 3. Boring or uninteresting because overfamiliar. - Oxford Dictionary）可指因体力或脑力消耗太多而需要休息，还可指因长期做某事而失去兴趣。

Henry was so tired that he went to bed immediately after he went out.

Exhausted（1. Very tired; 2. (of resources or reserves) completely used up. - Oxford Dictionary）表达的疲惫程度最强，指因劳累过度而精疲力竭。

The exhausted engineer fell asleep on the bus.

Fatigued（Extreme tiredness resulting from mental or physical exertion or illness - Oxford Dictionary）所表达的疲惫程度比tired和weary强，表示由于过度劳累而引起疲乏，不能再继续下去。

He felt fatigued and didn’t want to say a single word.

Weary（1. Feeling or showing extreme tiredness, especially as a result of excessive exertion; 2. Reluctant to see or experience any more of; tired of.- Oxford Dictionary）语气比tired强，指由于长时间努力工作或由于做单一的事儿引起疲倦。

After a long and weary wait, the plane finally came to take them.