decrease和reduce的区别：含义不同、词性及用法不同、侧重点不同。decrease可作名词和动词，含义为“减少”、“降低”、“减少量”；reduce只作动词，含义为“缩小”、“使蒸发”、“节食”、“使还原”。

decrease作为名词和动词，意为减少;(使大小、数量等)减小;降低；减少量。

例句：This species of bird is decreasing in numbers every year.

这种鸟的数量在逐年减少。

People should decrease the amount of fat they eat.

人们应减少脂肪的摄入量。

There has been some decrease in military spending this year.

今年的军费开支有所减少。

The rate of accumulation decreases with time.

积累的速度随着时间变慢。

Gradually decrease the amount of vitamin C you are taking

逐渐减少维生素C的服用量。

We've got stable labor, decreasing interest rates, low oil prices.

我们拥有稳定的劳力、不断降低的利率以及低廉的石油价格。

Contrary to popular belief, moderate exercise actually decreases your appetite

与通常的看法相反，适度的运动事实上会降低食欲。

reduce作为动词，意为减少;缩小(尺寸、数量、价格等);(使)蒸发;减轻体重;节食;使还原。

例句：Giving up smoking reduces the risk of heart disease.

戒烟会减少得心脏病的风险。

It reduces the risks of heart disease...

这降低了患心脏病的风险。

They were reduced to extreme poverty...

他们陷入极端贫困的状态。

He was reduced to begging for a living.

他不得不以乞讨为生。

All the buildings in the town have been reduced to rubble...

城里所有的建筑都成了废墟。

Boil the liquid in a small saucepan to reduce it by half...

用小炖锅炖，收一半汤汁。

Her challenge reduced them to silence.

她的质问让他们哑口无言。