From Avocado Hills: Slangbot is an urban dictionary for your iPhone, iPod Touch and iPad.
Pima cotton, also called extra long staple (ELS), is a type of cotton grown primarily in Peru, the southwestern United States and Australia. It is considered to be one of the superior blends of cotton and is extremely durable and absorbent.
Both are generally considered good quality, but there are some distinctions. Egyptian cotton refers to the country it was grown in. In this case, it's Egypt (oddly enough). Egypt produces many types of cotton, only about 20% of which is Pima cotton.