Coots and moorhens are both medium-sized waterbirds that belong to the rail family. They both have dark plumage and are found in similar environments. When seen together it is easy to tell them apart, but unless you know which identifying features to look for, solitary species may be a little trickier.
Coot

White frontal shield and bill
1 of 3Black plumage that can appear grey
2 of 3Large, lobed grey-green legs and feet
3 of 3The coot is slightly bigger than the moorhen, although there is some overlap so size is not a reliable identifying feature.
The simplest way to identify a coot is by the white shield that covers its forehead and its pale pink bill. Its plumage is black but can look grey in certain lights.
It has grey-green legs and large grey feet which are lobed.
Moorhen

Red frontal shield and bill with yellow tip
1 of 4Brown plumage on back
2 of 4White stripes on its flanks
3 of 4Bright yellow legs with chicken-like feet
4 of 4The moorhen has a red frontal shield and bill with a yellow tip. It has a brown tinge to its upperparts and white stripes on its flanks and white underneath its tail.
It has bright green or yellow legs with feet that look a bit like that of a chicken.