In my opinion, the meanings are similar, but there is more of request in the "will" form.
If I wrote to someone:
"Will you come home tonight?", would it imply an invitation, even without using the word "please", as opposed to:
"Are you coming home tonight?".
Imagine there is no body language, no facial expression, no intonation.
I'm just trying to find the subtle difference (if any!) between the two sentences.