A variation on something is the same thing presented in a slightly different form.
例句
This delicious variation on an omelette is quick and easy to prepare...这种稍加变化的可口煎蛋卷做起来又快又容易。Many theories on punishment exist, all of which are variations on a theme.关于惩罚的理论有很多,虽形式略有不同,但其主旨都是一样的。
N-VAR
(等级或数量的)变化,变动,变更
A variation is a change or slight difference in a level, amount, or quantity.
例句
The survey found a wide variation in the prices charged for canteen food...调查发现食堂饭菜的价格相差很大。Every day without variation my grandfather ate a plate of cold ham.我的祖父每天都会吃一盘冷火腿,雷打不动。