这两者可指“更多”。

many more后接一个名词一定是个复数可数名词。若不接名词，则more本身就被看作是一个复数名词，表示复数概念。如：
Some students are against the plan, but many more support it. 一些同学反对这项计划，但是有更多人支持它。
We have many more left. 我们还剩下很多。

much more后接一个名词，这个名词一定是个不可数名词。若不接名词，则more本身就被看作是一个不可数名词。如：
The farmers have produced much more rice. 这些农夫收了更多的稻谷。
She has much more to do. 她还有很多事要去做。

many more不可能修饰形容词和副词，而much more和far more, even more, still more 等一样，可以修饰形容词和副词，表示“更加”。如：
This TV set is much more expensive. 这台电视机要贵得多。
He worked much more carefully on the new design. 在这项新的设计上，他工作努力得多了。