reduce 和 decrease 有什麼分別 ？

reduce 和 decrease 兩個字雖然解 “減少”, 有時可以互用
最大分別是 reduce 不是 noun, 只可以做 verb, decrease 可以是 verb 和 noun
decrease 多數用在 number, amount, size
reduce 用途比較廣. 尤其用在 abstract noun

Population growth is decreasing by 1% each year.
The number of people visiting the Ocean Park has decreased gradually.

Her lawyers got the charge reduced from murder to manslaughter. ~ 不會用 decreased
All the shirts were reduced to $50. ~ 不會用 decreased

reduce 還有其他的 meaning.
下列 reduce 不可能使用 decrease 代替

使變為, 使變弱, 使陷落
The girl was reduced to tears [terror, silence]
The old man is reduced to begging for a living.
They were reduced from wealth to poverty almost overnight.
Not all information can or should be reduced to a number.
All the buildings in the town have been reduced to rubble.

【數學】簡[約]化
You can reduce 2/4 to 1/2.
Please reduce an equation to its simplest form

【化學】使還原
In the human body, nitrate is reduced to nitrite by the digestive system.
The H+ ions, with an oxidation number of +1, are reduced to H2


Reduced price (折價), 不是 decreased price
Reduced sentence (减刑) 不是 decreased sentence,

Reduce 是動詞，人為干預，decrease 是名詞，是現象，天作怪。

後者也用於數字。

The number decreased.

http://www.tribuneindia.com/news/uttarakhand/number-of-students-in-govt-schools-falls/65092.html

兩個都可解作減少,但較常用reduce,後者用於百分比