1. The Whooper. Cygnus musicus.
2. The Mute Swan. Cygnus olor.

Heads of mute swan and whooper swan
Date 1908
Source The Indian Ducks and their Allies
Author Henrik Grönvold (1858–1940); John Gerrard Keulemans (1842–1912)
Source: https://commons.wikimedia.org/wiki/File:Swan_heads.jpg

Cygnus musicus
The whooper swan (Cygnus cygnus) is a large Northern Hemisphere swan. Whooper swans require large areas of water to live in, especially when they are still growing, because their body weight cannot be supported by their legs for extended periods of time. The whooper swan spends much of its time swimming, straining the water for food, or eating plants that grow on the bottom.

Cygnus olor
The mute swan (Cygnus olor) is a species of swan and a member of the waterfowl family Anatidae. Cygnus olor is native to much of Eurasia, and (as a rare winter visitor) the far north of Africa. Cygnus olor is an introduced species in North America, Australasia and southern Africa. The name 'mute' derives from it being less vocal than other swan species.