1.从含义上说, almost强调“十分接近”,而nearly强调“尚有不足”,所以在表示“想要做而没做成”“很可能发生但还未发生”时,要用nearly; 而表示“简直”“像”等意思时,要用almost。例如：
I nearly committed a great error.我几乎犯了大错。
Please wait a minute.I'm almost out of breath.请等一下,我简直喘不过气来了。
It was almost like a dream.这简直就像一场梦。
试比较以下两句：
I nearly fell off my bike.
我差一点没从自行车上掉下来。
I almost fell off my bike.
我几乎从自行车上掉下来。
另外,修饰表示思想感情的动词时,只能用almost。例如：
He almost dreaded a visit to the doctor.他几乎害怕去看病。
She almost wanted to leave here.她几乎想离开这里。
2.从程度上说, almost比nearly更接近。例如：
We're nearly there.
我们快到了。
We're almost there.
我们马上就要到了。
I'm nearly as clever as you.
我快赶上你那么聪明了。
I'm almost as clever as you.
我差不多和你一样聪明了。
It is nearly time for class.
快到上课的时间了。
(如8点上课,现在是7：50)
It is almost time for class.
差不多是上课的时间了。
(如8点上课,现在是7：58)
3.从使用场合上说,在有趋势向某个目标发展的情况下,两者可互换。而在没有这种趋势或根本不可能达到的场合下,则只能用nearly而不能用almost。例如：
我们这只猫什么都懂,快赶上人了。
［误］ Our cat understands everything— she's almost human.
［正］ Our cat understands everything— she's nearly human.
我姑姑说话简直像个外国人。
［误］ My aunt almost sounds foreign.
［正］ My aunt nearly sounds foreign.
4.从语气上说, almost只是一般陈述; 而nearly则具有较明显的惊讶、抱怨等感情色彩。试比较以下两个句子：
差不多花了我一百元钱。
It cost me almost a hundred yuan .
(说说而已)
It cost me nearly a hundred yuan .
(太贵了)
It's almost 40 minutes' walk to the park.
走到公园差不多要40分钟。(陈述事实)
It's nearly 40 minutes' walk to the park.
走到公园差不多要40分钟哩!(太远了)
5.与no, none, nothing等连用,只能用almost而不能用nearly; 反之,与not, never连用,只能用nearly而不能用almost(但美式英语可说almost never)。例如：
There are not nearly enough people here to do the job.干这活儿,这些人手还远不够。
We almost never traverse tortuous paths.(AmE)我们难得走弯路。
6.在more than, too前用almost,不用nearly。例如：
That's almost too much!那简直太过分了!
This is almost more than we feared.这简直远远超过我们所害怕的情况。
7.nearly可加very, pretty等修饰,而almost不可。