你写的这些，在实践中都可能遇到，意思也差不多，只是某些更常见，某些不太常见而已。reduce侧重量或程度的减少，其他几个词侧重缓解，减轻。reduce suffering在英语里很常见。我给你几个外刊例句：

动词ease, alleviate, relieve和reduce的区别如下：供网友参考

【1】ease：表示在某种令人不愉快或者令人痛苦事情在程度，速度或者强度上减少或者降低。【宽慰；减轻；缓解；减少，降低】

Tensions had eased.紧张关系有所缓和。

This should help ease the pain.这该有助于减轻痛苦。

The plan should ease traffic congestion in the town.这项计划对城里的交通拥挤状况应该有所缓解。

The heavily falling snow had eased.漫天大雪变小了。

It would ease my mind to know that she was settled.知道她已安顿下来会使我放心些。

The pain immediately eased.疼痛立刻减轻了。

【2】alleviate：是指减少疼痛和受苦；减轻不愉快的程度使它们不是那么强烈和严重。 【减轻；缓和；缓解】

Nowadays, a great deal can be done to alleviate back pain.  如今，减轻背部疼痛可以有许多方法。

They always have the problem of alleviating mass poverty.  他们一直都有摆脱普遍贫困的难题。

A number of measures were taken to alleviate the problem.采取了一系列措施缓解这个问题。

 【3】relieve：是指令人不快的感觉在程度上变低或者下降或者说完全彻底消失【缓和，缓解，减轻，解除】

Drugs can relieve much of the pain.药物能够大大地缓解病痛。

This medicine has already relieved the symptoms of a cold这个药物已经减轻感冒的症状。

Tom has many ways to relieve anxiety ,guilt and stress汤姆有很多方法去消除焦虑 ，内疚和压力

Being able to tell the truth at last seemed to relieve her.能够最后讲出真话似乎使她感到轻松。

This should save her from boredom and will also relieve the pressure on you to keep her entertained.  

这能使她不会感到厌倦，而且也会减轻你的压力，不必总想着逗她开心。

【4】reduce: 是指在尺寸大小上，在数量上，在价格上，在程度上，或者发生概率上，使某物/某事变得更小，更少，程度更低，更便宜或者更低。【减少；减小；减轻】

 If you reduce something, you make it smaller in size or amount, or less in degree.

It reduces the risks of heart disease.这降低了患心脏病的风险。

Consumption is being reduced by 25 per cent.消费下降了25个百分点。

Costs have been reduced by 20% over the past year.过去一年，各项费用已经减少了20%。

Giving up smoking reduces the risk of heart disease.戒烟会减少得心脏病的风险。

The number of employees was reduced from 40 to 25.雇员人数从40人减少到了25人。

The skirt was reduced to £10 in the sale.在大减价期间，这条裙子减价到10英镑。