Lots of people have asked the question of does the length of cotton fibers really have an effect on the quality of the sheets made with cotton. The answer is ELS (extra long staple) cotton makes far superior sheets. The longer the fibers, the stronger the thread is; the longer the fibers, the better feel it has with much less thread counts.
Extra long staple cotton is about 1/3rd longer than regular cottons such as common American Upland cotton. Giza cotton is the longest and highest diameter cotton available on the market, making the best quality sheets in the world by far.
Giza 45 is not the only ELS cotton; there are many different ELS cottons in the world. We have Pima cotton in the US, China has some ELS strains, as does Turkey and other countries, but Giza 45 is so rare it demands incredible prices.
Reality is you can buy Pima or Turkish cotton and get very similar quality at a fraction of the cost. Where the cotton is processed and woven also has a major effect in quality. You will find that in most cases, Giza cotton is processed into threads and the weave is done in Italy. The Italians have 5, 10 and even 15 generations of professionals whoses families have been in the weaving business in Italy.