decline和decrease的区别在于中文含义上。decline可作名词和动词，中文含义有减少、下降、衰退、婉言拒绝，除了指数值上的下降，还能指能力等抽象量的下降，多指经济方面；decrease中文含义有降低、减少量等，专指数值上的下降减少。
一、decline的中文含义及双语例句
1、可作名词，意思有(数量、价值、质量等的)减少，下降，衰落，衰退。
例句：The company reported a small decline in its profits.
公司报告其利润略有减少。
An increase in cars has resulted in the decline of public transport.
汽车的增加导致了公共交通的减少。
Industry in Britain has been in decline since the 1970s.
英国工业自20世纪70年代以来一直在走下坡路。
2、还可作动词，意思有减少;下降;衰弱;衰退;谢绝;婉言拒绝;(根据名词、形容词或代词在句中的作用)变格，使发生词形变化。
例句：Support for the party continues to decline.
对该党的支持继续下降。
I offered to give them a lift but they declined.
我主动邀请他们搭车，但他们婉言谢绝了。
Their spokesman declined to comment on the allegations.
他们的发言人拒绝对这些指控加以评论。
二、decrease的中文含义及双语例句
1、可作动词，意思有(使大小、数量等)减少，减小，降低。
例句：The price of wheat has decreased by 15%.
小麦价格降低了15%。
People should decrease the amount of fat they eat.
人们应减少脂肪的摄入量。
This species of bird is decreasing in numbers every year.
这种鸟的数量在逐年减少。
They decreased their production in an attempt to push the prices.
他们减少生产量，以试图抬高价格。
2、还可作名词，意思有减少;降低;减少量。
例句：There has been some decrease in military spending this year.
今年的军费开支有所减少。
Significantly decreasing an action is also a type of exaggeration.
合理的减小动作幅度也是夸张的一种表现形式。
