Though Ubuntu has a handy AMI browser, some people prefer to use the AWS console to kick the tires. Ubuntu images are now displayed in the AWS Quickstart wizard on AWS.
Since many people provide Ubuntu AMIs on AWS we’ve branded the official Ubuntu images as “Ubuntu Cloud Guest”, while other images that are based on Ubuntu are branded as “Ubuntu”. Official images are also using the Orange Circle of Friends, the rest are using the Black Circle of Friends. We hope this makes it easier for people to differentiate between official AMIs and AMIs provided by others.
As always you can also browse cloud-images.ubuntu.com/releases/ directly, or use the command line tools to find the AMI you want.