difference between 'be coming' and 'will be coming'?
come, leave, arrive等瞬间动词本身没有进行时，用在现在进行时当中表示将要发生的动作。
即： be coming/leaving/arriving意思是将要来，将来离开，将要到达。
will be coming/leaving/arriving 同样表达将会发生的事。
两者的具体区别是什么？For example:
-He is coming tomorrow?
-He will be coming tomorrow?
How do the above two sentences mean/sound differently?

Question

difference between 'be coming' and 'will be coming'?
come, leave, arrive等瞬间动词本身没有进行时，用在现在进行时当中表示将要发生的动作。
即： be coming/leaving/arriving意思是将要来，将来离开，将要到达。
will be coming/leaving/arriving 同样表达将会发生的事。
两者的具体区别是什么？For example:
-He is coming tomorrow? 
-He will be coming tomorrow? 
How do the above two sentences mean/sound differently?

Answer

具体区别是什么？
1) -He is coming tomorrow. -- present continuous, 这是现在进行时态的句子, 这里"tomorrow" 是辅助字。主要用于表达在说话的时候正在发生一些事情的想法。也描述了活动的进展（而不一定是说话的时候）。
2) -He will be coming tomorrow. -- future continuous-- 我们主要使用未来的连续性来表示我们将在未来的某个特定时间里做某事

另外的应用，礼貌的问
Will you come home? (= “我想要你回家”的意思)
Will you be coming home? (=  我只想知道。。。)

Answer

The future continuous - will be + -ing is rarely used.  It's main purpose is to tell others what activity you will be doing at a specific future time

e.g. I am going on holiday tomorrow.  This time tomorrow evening, I will be having a drink in the hotel bar, thinking of you all!

As the example shows, this tense helps us to imagine the future situation.

Answer

Hi Gary, actually my question is: eg. Does "He's coming" mean the same as "He will be coming" ? If no, what's the difference then?

Answer

I don't understand your question well enough to answer it. But I can say that 'be xxx' is almost never used, as 'be' is always conjugated, e.g. I am coming. He is leaving.
Do you know about perfect tenses?