I have what appears to be the same iMessages on my iPhone 6 and iPad, 2nd generation. Yet, when someone writes me a message, it only appears on my iPhone and not my iPad (although I have a whole list of names who I have already corresponded with on my iPad).
If I receive it on my iPhone, why do I not get it on my iPad? And why can't I compose a new message from my iPad (the send button it greyed out).
It's a lot easier for me to respond with my iPad because it has a keyboard and some people prefer to send me messages on my iMessage against my messenger.
I went to Settings and they correspond to each other.