How to clone my 3tb external hard drive to another

now I would like to transfer the data from one hard drive to another and my computer will dont detect the new hard drive what can I do.

Both hard drives are 3tb and of the same model and what windows version do you have?

Yes, both hard drives are of the same tb and model. I have windows 7 and windows thinks its the same hard drives cause it shows that both hard drives are connected to the same E drive