What is the difference between Marginal, Bog, and Floating plants?

Marginal plants: plant material which grows and thrives around or near water. Ex. Hosta sp. Fern sp.
Bog plants: plant material which grows and thrives at depths of 8"-12" in water. Ex. Iris pseudacorus, Orontium aquaticum.
Floating plants: plant material which grows and thrives on the surface of water. Ex. Water lettuce, Water lillies