The simple answer is that alcohol causes hangovers. Wine contains alcohol: the more you drink the more you effect it will have. But not all wine contains the same amount of alcohol.
Darth Vader says he can drink lots of German wine without effect - well German wines have the lowest alcohol levels, up to 10% alcohol whereas French Reds are 12% and upwards. And alcohol levels are rising, table wines with 14-15% are common.
So check the alchol level on the label.
Also, other factors can affect the intensity of the hangover, the extra bits in the wine that gives it its flavour, so red wine has more of those. Plus some people might be affected by sulphur dioxide; this is in all wines to some extent.
But as my old Gran used to say, if you can lie on the floor without holding on, you're not really drunk :)