首先我们来看下be busy doing sth和be busy with sth的大致意思：
be busy doing sth：词性为短语，be busy doing sth是be busy的一种特殊用法，其中doing sth是动词-ing形式的短语作为宾语补足语。
be busy with sth：词性为短语，be busy with sth表示某人正在忙于处理或从事某个具体的事务，sth表示具体的事项。
通过下面的表格我们了解下be busy doing sth和be busy with sth的含义、发音和用法
接下来让我们看下be busy doing sth和be busy with sth的用法区别：
1.语法结构：be busy doing sth是动词-ing形式作为宾语补足语，而be busy with sth则是表示某人忙于处理或从事某个具体的事务。
例子：
-I am busy writing a report.
(我很忙于写报告。)
-They are busy with preparing dinner.
(他们正忙于准备晚餐。)
2.语义差异：be busy doing sth强调正在进行某项活动，而be busy with sth强调忙于某个具体事务。
例子：
-I am busy learning new skills.
(我很忙于学习新技能。)
-She is always busy with handling the company's daily affairs.
(她总是忙于处理公司的日常事务。)
3.语用场景：be busy doing sth常用于描述个人的忙碌状态，be busy with sth常用于描述具体的工作或事务。
例子：
-He is busy writing his thesis every day.
(他每天都在忙于写论文。)
-We are busy with organizing the conference.
(我们正忙于组织会议。)
4.语法搭配：be busy doing sth后面通常接动词-ing形式的短语作为宾语补足语，而be busy with sth后面通常接名词短语或动名词短语作为宾语。
例子：
-I have been busy reading books.
(我一直忙于读书。)
-They are busy with solving technical issues.
(他们正忙于解决技术问题。)