Chords must have same tone in both keyboard and guitar. I have seen some people play chords a little different in keyboard in the sense that a few chords sounds better in guitar and others in keyboard, but it's within the same scale so I would think it really shouldn't matter which instrument plays them. Sometimes it's just the feel of your voice. For ex. D minor may sound better for you, whereas maybe if you play Em its much better in piano. But if you look at the overall chord structure within the song, it's what suits you best. Hope that makes sense.