一、从词性用法上比较
1.good 只用作形容词,不用作副词,其副词形式用 well.如：
He speaks good English.他的英语说得好.
He speaks English well.他的英语说得好.
2.well 既可用作副词,也可用作形容词.用作形容词时,其用法很有限,只表示“健康的”“恰当的”或“令人满意的”等.如：
She is very well.她身体很好.
Things are well with us.我们事事如意.
注：一般说来,well 用作形容词时,只用作表语而不用作定语(如上例),但在美国英语中,well 表示“身体健康”时有时也可用作定语.
二、从相关短语用法上比较
be good at 与 do well in：两者均可表示“擅长”.如：
He is good at languages.他擅长学语言.
She is good at telling stories.她擅于讲故事.
They all did very well in the examination.他们这次都考得很不错.
注：表示擅长某一学科时,也可用be good in.如：
He is good at [in] maths.他擅长数学.
2.as good as 与 as well as：用于本义时,两者均可表示“与……一样好”,但 good 是形容词,而 well 是副词.如：
他说英语说得跟她一样好.
正：He speaks English as well as her.
正：His English is as good as hers.
但是,用于引申义时,两者的意思很不相同：as good as 意为“几乎”“差不多”(=almost),as well as 意为“而且”.如：
The work is as good as finished.工作差不多干完了.
He as good as said I’m a liar.他无异于说我撒谎.
She’s clever as well as beautiful.她不但漂亮,而且聪明.
As well as breaking his leg,he hurt his arm.他不但摔断了腿,而且还伤了胳膊.