Somewhat similar Pied-billed Grebe has a thicker bill and brown crown, nape and back and dark eyes. A dark winter-plumaged Eared Grebe would stand out as larger, with a white breast and foreneck, a red eye, and a prominent crest. Other grebes are larger and have quite different plumage.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.