no more than

no more than  adv. 只是 
not more than  n. 至多 .(仅仅,不超过) 

这两个词的用法及区别,很明显是不一样的.
no more than:是相当于一个“副词”（adv.）。意思是：“ 只是”
例如: I am no more than a worker. 
我仅仅是个工人。

分开用时表示no more ... than-“ 和......一样不(否定两者)、正如…… 一样不(否定两者)”。
He is no more deligent than I am.
他和我一样不勤奋。

not more than：是相当于一个“名词”（n.）。意思是: “至多” 
例：The experiment was done by not more than 5 persons.
做这个试验的人至多5个 

not more ... than = 不如

no more ... than = 和......一样不(否定两者)

not less ... than = 不如......不（即指不如 less 后形容词的反面）

no less ... than = 和......一样(肯定两者)

比较以下各句的意思：

You are more careful than he is. 你比他仔细。

You are not more careful than he is. 你不如他仔细。

You are no more careful than he is. 你和他一样不仔细。

You are less careful than he is. 你不如他仔细（你比他粗心）。

You are not less careful than he is. 你比他仔细（你不如他粗心）。

You are no less careful than he is. 你和他一样仔细。