I can't connect my iphone 4 to my iPad 3 instead of using up all space on my iPad just thought I could play my music via Bluetooth from iPhone

The Apple Support Communities are an international user to user technical support forum. As a man from Mexico, Spanish is my native tongue. I do not speak English very well, however, I do write in English with the aid of the Mac OS X spelling and grammar checks. I also live in a culture perhaps very very different from your own. When offering advice in the ASC, my comments are not meant to be anything more than helpful and certainly not to be taken as insults.

iOS devices do not natively have this ability. There was a 3rd party app called AirFrame which used the AirPlay in iOS to allow this from one iOS device to another, but it is no longer available in the iTunes App Store. So unless someone comes up with another app, I think that you are out of luck.

I use my iPad for all videos, movies, TV shows and music videos and I use my iPhone for music only.

Dah:veed is right about this. I am sure Apple has prevented this ability because you could then share your music, videos, etc. with any iPad/iPhone you could pair with using bluetooth. And as we all know, sharing music is illegal and not allowed.

All of the ways that Apple has our devices locked down and locked to iTunes is, I am sure part of Apple's contracts with the studios to ensure that their hardware isn't easily being used to pirate content.