级差的英文：
gradation
stage head

参考例句：

They pay differential rents according to their income.
他们根据收入多少付级差房租。

During the Second World War, industrial wage differentials in Britain widened.
第二次世界大战期间，英国的劳工工资级差进一步拉大了。

gradation是什么意思：
n. 渐变；阶段；等级；刻度

A small variation,gradation,or difference.
细微差别小的变化、颜色深浅或不同

(The gradation and classification of agricultural land in China)
11、中国农用地分等定级

It was hard to understand all the minute gradations of their bureaucracy.
很难弄清楚他们那套官僚体制全部细微的等级分别.

stage是什么意思：
n. 阶段；舞台；演员的职业；事件发生地；站，架，层；上演
v. 上演；举行；展现；筹划

As the elapse of time, their feeling warms up stage by stage.
随着时间的推移，他们的感情逐步升温。

stage well [Badly]
很[不]适于上演

She was mad about the stage.
她狂热地迷恋着舞台生活。

head是什么意思：
n. 头，头部；头痛；理解力；首脑，首长
v. 作为…的首领；站在…的前头；给…加标题；出发；前进；驶往；用头顶
adj. 头的；在前头的；在顶端的；主要的；首要的

Heads will roll

a head of a gang; a ringleader; a chieftain; the head of a group; a cock
头目

They hit their heads together when heading the ball.
争顶头球时，二人的头撞在了一起。