两者可比性不大。

一、形式区别：

doing （现在分词或动名词）

to be doing （动词不定式的进行体）

二、用法区别：

1. doing ，由于是现在分词或动名词，所以，除了作主语、宾语、表语、定语、各种状语外，还构成各种进行时，例如：

We are having an English lesson now. 我们现在正在上英语课。

At that moment,we were having a party. 那个时候，我们正在举办聚会。

How long have you been living here? 你住在这儿多长时间了？

I had been waiting in the room for half an hour before she turned up. 在她出现之前，我在房间里等了半个小时。

This time tomorrow，I shall be flying to Shanghai. 明天这个时候我正在飞往上海的途中。

They would be discussing the plan the next day. 他们将在第二天讨论这个计划。

2. 不定式的进行体：to be doing

不定式的进行体表示的动作，与谓语动词表示的动作同时进行。

He seems to be worrying about something.（=It seems that he is worrying about something.）他似乎正在担心什么事。

Don't pretend to be working hard.Just do what you should. 不要假装努力工作。做你该做的事。