HDD stands for Hard Disk Drives, which store data on magnetic disks. SSD stands for Solid State Drives, which store data in flash memory and have more volume, speed , and efficiency than HDD.
IOPS are measured by input/output operations per second, and it is calculated by numbers (KiB).
Yes, we can attach multiple volumes to an EC2 instance.
Yes, it's possible to detach the additional volume not the root volume.
Throughput is defined as the speed of the data processing calculated by Mbps. In simple terms, data processing is measured by the size of the data.