Yeah that is similar to Aurora. Basically a query engine on top of S3. Not sure if it is based on postgres or not though. It wouldn't shock me if it was as I know AWS Redshift is a forked version of postgres.
Looks like I was mistaken. It uses some parts of postgres 8, but it is heavily modified. I agree Redshift isn’t that great though and it is super expensive for what you get. In the past when I have used Redshift I have not been that impressed.
Although one nice feature of Redshift is how well it works with other AWS services (COPY command from S3, firehouse can dump data into it, etc.)