Grebes are aquatic diving birds of freshwater and, at Seaton anyway, brackish water habitats.
Rails are a large family of small- to medium-sized, ground-living birds. Those I include here all are wetland species.
Little grebes dive for small fish, insects and aquatic molluscs
The Tower hide at Seaton gives a view from above, showing a Little grebe as it dives for food.
Coots are also diving birds with broadly lobed toes similar to the grebe's. They eat grass, seeds, shoots, snails, tadpoles and small aquatic invertebrates.
Moorhens feed on land and in water. They swim but do not have the webbed of lobed toes of the Little grebe and Coot. As far as I am aware, they do not dive routinely so probably do not need the extra propulsion. They eat seeds, fruits, roots, snails and insects.
Water rails are mostly secretive and elusive rather than shy, living in dense vegetation such as reeds and overgrown pools. Water rails will eat small birds, voles and dead animals, insects and molluscs, plus seeds and berries.
In a futile quest for the perfect Kingfisher photo, I waited impatiently in the Seaton Classroom bird hide long enough to get these shots of a Water rail. A fair compensation! The Kingfisher will have to wait.