Countries classify their peatlands differently, but most agree on two main classes: bogs and fens (with some swamps being a third).
Bogs are unique as they are the peatland class that can only receive water from precipitation (no other sources). This is makes them ombrogenous (from the Greek, ombros, meaning shower of rain and genous meaning origin) or rain-fed. It also helps explain their low nutrient status and ombrotrophic vegetation.
Fen peatlands, however, can also be ombrogenous (a poor fen for instance), but can more typically receive surface water (e.g., a stream) or groundwater discharge (like a spring), making them geogenous (from the Greek geo, meaning earth).
Most commonly known special peatland types are e.g. aapa mires, blanket bogs, palsa mires, spring fens, and tropical peat swamp forest. Many languages have special peatland expressions with even regional differences.