The two main kinds are discrete and continuous.
Lion,Cheetah and Tiger.
there are far more than two main kinds of submarines. The only two sections I can think of to separate them are fast attack and Boomers or Ballistic Missle.
consumers and producers.
kinetic and potential
indentured and chattel .|.
fat and fur
cat and dog
quiet and explosive
The two main types of swamp are "true" or swamp forests and "transitional" or shrub swamps.
Sail boats and power boats are the two main types of pleasure craft.
You tell me!