Size and Appearance
Bewick's Swan is medium-sized, 105–125 cm long with an 185–205 cm wingspan. Whooper Swan is larger, 140–160 cm long with a 200–240 cm wingspan.
Bill
Bewick's has a yellow bill with a black tip; the Whooper has a yellow bill with a black base.
Head and Neck
Both have mostly white heads and necks, but the Whooper has more extensive yellow around the eyes and lores.
Voice
Bewick's makes a high-pitched trumpeting sound; the Whooper's call is lower and more sonorous.
Distribution
Bewick's breeds in Arctic Russia and winters in western Europe and the Caspian region. Whoopers breed across Arctic Europe, Asia, and North America and winter in those continents.
Diet and Conservation
Both are herbivorous and listed as Least Concern by the IUCN.