You can now launch R3 and T2 instances when using Amazon RDS for MySQL,MariaDB, PostgreSQL, and Oracle and SQL Server in the AWS GovCloud (US) region. R3 instances are optimized for memory-intensive applications and own the lowest cost per GiB of RAM among the Amazon EC2 instance types. T2 instances provide a baseline level of CPU performance with the ability to burst above the baseline. The bursting model is based on “CPU Credits” that accumulate during quiet periods for spending when things glean busy. to memorize more about the benefits of the R3 and T2 instance families on Amazon RDS,visit the documentation page. For more information on pricing, visit the pricing page.
Source: amazon.com