General Purpose SSD (GP2) – price and performance balance
Provisioned IOPS – SSD (IO1) designed for high I/O applications. For example, large relational + NoSQL DB more than 10,000 IOPS
Throughput Optimized HDD (ST1) Magnetic Storage = Old school physical spinning disks. For example, Big Data, & OS processing, data warehousing. Main thing to note is that this cannot be boot volumes.
Cold HDD (SC1) (magnetic Storage) Lowest cost storage for infrequently accessed workloads.