They are two different tenses. Future tense and Future continuous tense. You could look those up for details and examples. The basic difference is that 'will be doing' is used to refer to a longer time - to indicate that doing it will take some time, or to indicate that is what you will be doing over a certain period. So - 'When will you fix that lightbulb' - I will do it tomorrow. 'I will be doing' doesn't make much sense, as it only takes a few minutes to do. It's possible, but unlikely. 'What are you doing at lunchtime tomorrow'? 'I will be doing my homework'. That indicates that you will be spending most of your lunch break doing homework (and therefore won't have any time to do anything else).' When are you going to fix my computer? 'I will do it tomorrow' - means that it will hopefully be fixed tomorrow. 'I will be doing it tomorrow' means that it will be ready maybe tomorrow or the next day, but it also suggests that it will take a substantial part of the day. It implies that it isn't just a few minutes job.

我听懂了GARY的回答，翻译给你： 前面是将来时态，后面是将来进行时态。 将来时是指你将来会做一件事情，这个事情会花一点时间就能完成，或者这个事情今天做了明天再做都可以，中间可以间断。 将来进行时是指你将来将会持续的做一件事情，这个事情中间不能间断，在此期间你是不能做别的什么事情了。

yes ,will be doing

Did you mean 'will be doing'?