Bogs are usually in isolated pockets, and covered in sphagnum moss, known as "quaking mats" . Walking in these is dangerous because a person can easily fall through the moss and there is nothing to grab onto to come back out. Bogs have very acidic waters. There are people who fell through the moss thousands of years ago and became red and "pickled"- they are known as "bog people".
According to the Ontario Ministry of Natural Resources and Forestry, which leads wetland evaluations and programming in Ontario, "Fens are Peatlands that are poorly drained, but slow internal drainage does occur. Dominant vegetation is sedges, but shrubs and sparse, short tree growth may be present. Waters are circumneutral or only slightly acid. Three basic types are found. (a) Graminoid Fen - Open, sedge covered fen, with less than ten percent (10%) cover of shrubs or trees. (b) Low Shrub Fen - Open fen dominated by shrubs such as leatherleaf and dwarf birch less than 135 cm high. c) Treed Fen - Canopy cover more than ten percent (10%), usually tamarack, and usually not of merchantable size. " We can generalize that in central and northern Ontario fens are very similar to bogs; they are sphagnum dominated, but are less isolated with some movement of water, and therefore with more nutrients that would support some tree species like Tamaracks or black spruce. Cotton grass that likes extremely acidic waters is not dominant in a fen but is often found throughout bogs, as are pitcher plants, sundews, and other sedges.
Fens of southern Ontario, the Carolinas and a few rare instances at the southern edge of The Land Between zone near the dolomite and limestone, are often more alkaline and result not so much from isolation and the consequent formation of carbonic acid, but from seepage areas and/or the upward movement of groundwater. These fens are often flat areas that are moist and dominated by sedges; and they may have soils that are very fine and "clayey" known as Maarl, which are tiny calcareous particles or deposits.
But overall both bogs and fens have very few plant species (low diversity) because of the acidity and/or lack of nutrients in these systems.
Spotted turtles and Blanding's turtles like these habitats. 
