Greater White-fronted Geese are 64–81 cm (25–32 in) in length, have a 130–165 cm (51–65 in) wingspan and weigh 1.93–3.31 kg (4.3–7.3 lb). They have bright orange legs and mouse-coloured upper wing-coverts. They are smaller than Greylag Geese. As well as being larger than the Lesser White-fronted Goose, the Greater White-fronted Goose lacks the yellow eye-ring of that species, and the white facial blaze does not extend upwards so far as in Lesser.
The male is typical larger in size, both sexes are similar in appearance – greyish brown birds with light grey breasts dappled with dark brown to black blotches and bars. Both males and females also have a pinkish bill and orange legs and feet.
The Greater White-fronted Goose is divided into four subspecies. The nominate subspecies A. a. albifrons breeds in the far north of Europe and Asia, and winters further south and west in Europe.
Two other restricted-range races occur in northern North America: A. a. gambeli in interior northwest Canada, and wintering on the coast of the Gulf of Mexico, slightly larger than the nominate form, and Tule Goose, A. a. elgasi, in southwest Alaska, largest and longest-billed of all, wintering in California. All these races are similar in plumage, differing only in size.
Finally, the very distinct Greenland White-fronted Goose, A. a. flavirostris, breeding in western Greenland, is much darker overall, with only a very narrow white tip to the tail (broader on the other races), more black barring on its belly, and usually has an orange (not pink) bill. It winters in Ireland and western Scotland.
Birds breeding in the far east of Siberia east to Arctic Canada, wintering in the United States and Japan, have been described as A. a. frontalis on the basis of their slightly larger size and a marginally longer bill. Another putative East Asian subspecies albicans has also been described. A 2012 study has found that frontalis and albicans do not merit subspecies status, the former being synonymised with gambelli and the latter with the nominate subspecies; this study fond that tehse forms had been named on the wintering grounds from specimens whose breeding grounds were unknown.
Recent ecological studies suggest the Greenland birds should probably be considered a separate species from A. albifrons. Of particular interest is its unusually long period of parental care and association, which may last several years and can include grandparenting, possibly uniquely among the Anseriformes.