We will join you in an hour. We will be joining you in an hour. What is the difference between them? I am bit confused about these sentences? What kind of meanings do these sentences give?
There is usually a difference between "will (verb)" and "will be (verb-ing)". However, for this specific example, there is hardly any difference. Let's take a different example sentence that will make it more clear.
In an hour, we will watch a movie.
In an hour, we will be watching a movie.
1) means "In an hour, we are going to start watching a movie."
2) means "When we start our movie is irrelevant, but in an hour we will be watching some part of the movie."
So with sentence 2, in an hour we might be at the start of the movie, we might be at the end, and we might be somewhere in the middle. But we will still be watching.
This is mostly irrelevant to your sentence because there is practically no difference between "we will start joining you" and "we will be in the middle of joining you". Because joining a group doesn't take over an hour like a movie does.
Both sentences sound fine and mean the same thing. Sentence 1 sounds more natural and more casual to me. Sentence 2 sounds a little bit more formal.
I think you will hear divergent views about the difference of your two sentences and one can interpret a lot about the difference that is not there.
For me there is only a difference of weight. 1 is the normal thing. And there is no sense in stressing a progressive aspect. If 2 is used it just has a bit more weight as the structure is longer. And some people simply have the habit to prefer the variant 2.