These are northern cardinals. Northern cardinals are also called redbirds or common cardinals. The redder one on the ground is a male. The browner one on the feeder is a female. They are mates. Cardinals mate for life, so Mr. and Mrs. Redbird in this picture will be together for the rest of their lives.
This bird feeder is in my backyard right outside our window. I got this bird feeder for Christmas. Mr. and Mrs. Redbird come all the time. We also see chipping sparrows, grackels, European starlings, American goldfinches, and purple finches at our feeder. The cardinals’ favorite feed is black oil sunflower seeds, and their favorite feeder is the fly-through feeder, which is the kind of feeder that Mrs. Redbird is sitting at in the picture.
Northern cardinals mostly live in the eastern United States, but they can be seen in Arizona and the west as well.