If you don't know what a UV sphere is, think of the quads in a rectangular world map, longitude by latitude, where the quads have different widths when they're mapped to the surface of a sphere. If you subdivide the quads into triangle pairs (of course the polar quads are already triangles) you get triangular faces of a polyhedron.

These quads and triangles are all different widths because the circumference varies by latitude but we're cutting the quads up by latitude, not width in miles or kilometers. As the world map is built up from either side of the equator the quads are shortened and subdivided into triangles.