There is no point. Yes, you can transfer the preset voice files from one keyboard to another but not the voice samples which those files need to link to in order to produce the correct sound.
So the files you transfer either won't work, or will play a substitute voice already present on the receiving keyboard or if they do it is because the receiving keyboard already had the samples and you could have played them anyway with no extra hassle.
Pointless.
If you want to find out which voices are common (or missing from) keyboards look through the voice nos. in the corresponding data lists. Where all 3 voice nos. for a particular voice coincide both keyboards already have that voice. If one of the boards does not show all 3 voice nos. that precise voice is not available, (although a related one with a similar timbre might be).
John