Generally quality by a little and price by a good bit. But you would expect that from the same company.
I actually love Old Navy - even more so before they started mixing in man made fabrics too much. It is a great place to teach your kids the joy and beauty of picking out their own clothes, why things go together, and developing their own style. And you can do it all for a reasonable price with clothes that will more than likely outlast their short time in them. Their tees and long sleeve tees were an awesome deal when they were 100% cotton.
Little bummed about this - I worked at both GAP and Banana Republic. When I first started at GAP fifteen years ago, one coul still acquire lots of basics - even preppy in style - for reasonable prices and the clothes were durable enough.
Things have gone completely off the rails now, and I'm not sure the brand can bring them back.