Most people confuse the over hand with the cross. Initially both punches have had the same idea, the cross actually comes from crossing the jab and has been a straight punch. But it has been developed to an over hand. The over hand has close, mid and long range. At the JT video that was posted you can its different ranges (I love trowing the close range one). What Golovkin does is trow a mid range overhand, however he trows also right hooks often as a counter to blocking or evading his over hand and cross so you can mix up recognising the shots. However the technique is similar from mid range over hand to mid range right hook. And since Golovkins coach is a Mexican - the answer is no - there is no Russian over hand. It is just that Golovkin has pretty damn good technique and you can recognise different range of motions due to his skills.