Infinite Sets. If you continue to study this subject you will find discussions about infinite sets, and the idea of different sizes of infinity. That subject has special names like Aleph-null (how many Natural Numbers), Aleph-one and so on, which are used to measure the sizes of sets.
For decades, glossy paper, the type used in magazines, was made using a white clay called kaolin (named after the Chinese region Kao-Ling where it was mined to produce porcelain).
When glossy paper has a smooth texture, lustre paper is slightly textured. In paper finishes also, they have differences. Glossy paper gives a shiny paper finish whereas lustre paper gives a soft, sheen finish. When comparing the quality, glossy paper gives a better quality than the lustre paper.