一般过去将来时
形式：would+动词原形；was/were going to+动词原形
用于描述过去的时间点上对未来事件的看法和猜想。

过去将来进行时
形式：would/should be doing
用于描述过去某个时间点对未来某时间正在发生的事情的猜想。

例句对比：
（1）
He said that she would have dinner with her friend tomorrow. 他说她明天会和朋友一起吃饭。
He said that she would be having dinner with her friend at 6 tomorrow. 他说她明天6点会在和朋友吃饭。

（2）
He said that he wouldn't come. 他说他不会来。
He said that he could not come because he would be having a meeting. 他说他不能来因为要开会。

（3）
You told me that Jack would finish his homework. 你告诉我杰克会做完他的作业。
You told me that Jack would be doing his homework tonight. 你告诉我杰克今晚会在做作业。

（4）
I knew that she would write a letter to her boyfriend. 我知道她会给她男朋友写信。
I knew that she would be wring a letter to her boyfriend. 我知道她正在给她男朋友写信。

（5）
He asked me what I would do tomorrow. 他问我明天会做什么。
He asked me what I should be doing six o'clock tomorrow. 他问我次日六点将正在做什么。

同一般将来时和将来进行时的区别一样，一般过去将来时和过去将来进行时的区别在于是否为持续性动作。请仔细留意从句中是否有具体的时间点。