A wine glass consists, from bottom to top: the foot, the stem and the chalice. The foot ensures that the glass stays put. The stem allows you to hold the glass and, finally, the chalice. The chalice allows for the retention and distribution of aromas.
A white wine glass is smaller and narrower than the red wine glass. The narrow glass allows the wine to stay cool longer. A red wine glass is wider, this allows enough oxygen to reach it and the wine develops in the glass. In order to roll well and thus give the wine extra air, it is important that the sphere of the chalice is also wide enough.