The two main types of swamp are "true" or swamp forests and "transitional" or shrub swamps.
swamps and marshes
The two main types of wetlands are marshes and swamps. Marshes are characterized by emergent soft-stemmed vegetation and open water, while swamps are dominated by trees and shrubs.
The two main kinds are discrete and continuous.
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 .|.
quiet and explosive
Sail boats and power boats are the two main types of pleasure craft.
The action verb and the linking verb.
bogs, fens, marshes and swamps
Eucalyptus and Australian acacia