for surviving, you 需要 food and water; if you 想要 a better life, you must work hard; i 希望 everything is fine. 要= 想要，需要，应该，必须，要求……

需要=I need something 想要=I want something 要= I will do somgthing or I need something 希望= hope/I hope ....

1.希望:wish/hope (when it is used as a verb) In Chinese it is different with others that it must be followed by a sentence,not a word or phrase. ex.1)我希望他送我一个礼物。(I hope he will give me a present) ex.2)我希望明天会更好。(I wish it is better tomorrow.) 2.需要 ：need/want In Chinese it can be followed by a word or a sentence.ex.1) 我需要一本中文书。(I need a Chinese book.) ex.2) 噢，亲爱的，我很伤心，我需要你。(oh,dear,I am so sad ,I want you are my side.) 3.要+noun means want/need/ask for ex.1)我要一杯茶。(I want a cup of tea.) ex2) 他要一个助理。(He needs an assistant.) ex.3) 我要个三明治。(I ask for a sandwich.) 要+phrase or sentence means ask for/be going to do sth. ex.1) 我要去北京。（I am going to Beijing）ex.2) 妈妈要我去商店。（Mom ask for me to shop.) 4.想要 can be followed by a word or phrase. 想要+noun means want to obtain something. ex.1)我想要一份礼物。（I want a gift.） 想要+verb.means want to do something.note:in this statement,想要 is more like an auxiliary verb,and 要 is often dropped ex.2)我想要去北京/我想去北京。（I want to go to Beijing） ex.3)我想要看电视/我想看电视。(I want to watch TV)

作为一个中国人，每次看到外国友人提出在学习中文时遇到的问题，我知道是什么意思，也知道怎么用，但是我很难用语言去表达，因为中文中，有个词语叫语感，我们很多时候去凭感觉。还有时候遇到中文中很美的意境，你可以想象，而语言很难表达，叫;只可意会不可言传。

(xuyao)is need .(xiangyao)iswant.(xiwang )is hope.or wish