It makes no difference to me.这个句子为什么difference不加s.

It makes no difference to me.这个句子为什么difference不加s.
1.差别,差异[C][(+between)]
Whether it rains or not makes no difference to me.
下不下雨对我来说都一样.
Can you tell the difference between an ape and a monkey?
你能区分猿和猴吗?
2.差,差距;差额[the S][(+between/in)]
The difference in temperature between the day and the night there is thirty degrees.
那里白天与黑夜的温差是三十度.
3.争论;不和[P1]
That is the root cause of all our differences.
那是我们一切分歧的根源.