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Vertebrates and invertebrates.
You haven't stated any categories.
Elephant and OSTRICH
The two main categories are convenience goods and shopping goods; two lesser categories are specialty items and unsought goods.
Deoxyribose and Ribose
descriptive and inferential
botany and zoology.
IT is separated into two main categories (1) those which process information, such as computer systems, and (2) those which disseminate information, such as telecommunication systems.
The two main categories of luster are metallic and non-metallic. Metallic luster appears shiny and reflective like metal, while non-metallic luster includes categories such as vitreous (glassy), pearly, greasy, and dull.
linear and non-linear resistor
animal and vegetable
It is not possible to answer as there are many more than 2 categories.