首先，more than与less than都是比较级，前者是升级比较，后者是降级比较，这个比较容易掌握；no与not都是表示否定的词，这也很明显。但两个否定词冠于比较级之前，所产生的意义又相差甚远。
no more than V.S not more than
I. 单独使用。
1. no more than：表示仅仅、只有，只不过，强调少，相当于only， 已失去比较意味;
He has no more than 2 children.
他只有2个孩子。（= He has only 2 children.）
It took me no more than a month to finish reading the book.
解译：我只花一个月时间读完那本书。（=only）
He is no more than a puppet.
他只不过是个傀儡。（=only）
There is room for no more than three cars.
这地方只能停放三辆车。
2. not more than：表示不多于、至多，最多；相当于at most，强调上限。
He has not more than three children.
他最多3个孩子。或许还不到3个，也可以说He has 3 children at most.
He has learned not more than 100 words.
他学会的词不超过100个。（最多才学100个）
Not more than fifteen students passed the exam.
最多十五名学生通过了这次考试。
I have not more than ten dollars.
我有不超过十元钱。
II. 用在比较级句中。
1. no more ... than：意为“A跟B一样都不怎么样”，是对双方都进行否定，相当于neither ... nor。
He is no more a writer than a painter.
他既不是画家，也不是作家。= He is neither a painter nor a writer.
A whale is no more a fish than a horse is.
马不是鱼，鲸也不是鱼。=Neither a horse nor a whale is a fish。
You can no more swim than I can fly.
你不能游泳正如我不能飞行一样。=You can not swim just as I can not fly.（二者均予以否定）
He is no smarter than you.
解译：他跟你一样脑子不灵光。（两个都不聪明）
2. not more ... than： 比较级否定式，意为“A不及B…”。
He is not smarter than you. 他不比你聪明。
no less than V.S not less than
I. 单独使用。
1.no less than: 多达、有……之多，强调多（与no more than意思相反）。
He made no less than $50,000 per month.
他月薪高达5万美元。（与比较无关，注意中文语气）
He has no less than seven daughters.
他的女儿多达7个。
2. not less than: 不少于，相当于at least, 强调下限。
He has not less than seven daughters.
他至少有7个女儿，不少于7个，即7个或更多，也可以说：He has at least 7 daughters.
II. 用在比较级句中。
1. no less…than：A和B一样…，对二者均予以肯定，相当于as… as… .
This song is no less popular than that one.
这两首歌一样受欢迎。对二者均予以肯定，相当于：
This song is as popular as that one.
Italian is no less a mother tongue than French for him.
意大利语和法语一样，都是他的母语。
这种句子读起来比较拗口，读者可以将no less… than这个结构先抽出来，下一步再对句子所涉及的双方做肯定处理。
2. not less… than: 降级比较的否定式，意为“不少于”。
This song is not less popular than that one.
这首歌受欢迎程度不亚于那首歌。含比较意味。
She is not less charming than she used to be.
她的魅力不减当年。