The House Finch, Purple Finch and Cassin's Finch are three similar species sometimes referred to as the red finches, in deference the color on the males.
The House Finch is common across most of the United States.
The Purple Finch breeds across most of Canada but is common in the winter in the eastern half of the U.S., as well as along the west coast.
The Cassin's Finch is a western species. The range of Cassin's and Purple Finches seldom overlap, but common occurences do occur.
The females of the three species are easier to identify than the males.
The female Purple Finch as a strong face pattern and strong streaks on the chest and sides.
The female House Finch has a very plain face, diffuse markings on the undersides and a somewhat conical bill.
The female Cassin's Finch has a pointed bill and strong streaking on the underparts.
Face pattern less distinctive than on Purple Finch.
The male Purple Finch has rose-red over much of the body, with diffused markings on the underparts.
The male House Finch has a noticeable gray/brown cheek patch.
Steaks on the underside are strong.
The male Cassin's Finch is much like the male Purple Finch.
Generally less red on the Cassin's with a red cap giving way to a brown nape.