They seem to be different. They have predefined circles (e.g. Family, Friends) and you can create others. However I don't see a Create a Circle from a Contacts

They seem to be different. They have predefined circles (e.g. Family, Friends) and you can create others. However I don't see a Create a Circle from a Contacts Group. I'm not sure if I would want that as I normally don't update my Contacts groups.