The Blue Grosbeak is very similar to the Indigo Bunting but is larger with brown wing bars. Female Indigo Buntings are similar to other female buntings. Female Lazuli Bunting has white wing bars. Female Varied Bunting very similar but has more curved culmen and lacks steaking below. Female Painted Bunting greener. Sparrows have more patterned faces and streaked backs.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.