I don't think theres much of a difference between Diego and VDV. Both were very good in the Bundesliga, both play primarily as attacking mids. I'd say VDV is the more versatile of the two, as he is able to play as CM and has at times played as a winger even if he is rather restricted there. Also VDV strikes me as the better passer of the ball, but Diego is the more flamboyant of the two, the better dribbler and the harder worker too.