This seems almost like a homework question ;p
Firstly there’s two main types of storage – hard drives and SDDs
With hard drives, in general there’s two things to look at – first is RPM – higher RPM is faster, but noisier and uses more power. The second is cache, more cache is generally better, and results in better performance.
With SSDs, information is stored on flash chips, usually NAND. In addition to transfer speeds, you’ll want to look at SLC (fastest, longest lived, most expensive, usually used in enterprise grade drives), MLC (‘normal’ flash storage) and TLC (uncommon at the moment, supposed to be cheaper, has the worst life). Most SSDs are faster than even the fastest hard drives, but the trade off is smaller capasities and higher costs.
Older devices (well, within the last 20 years or so) used IDE/ATA, which has been bacronymed to PATA or parallel ATA or SCSI. SCSI had multiple varients, and often needed terminators. Different types of scsi drives were incompatible with each other.
Modern devices usually use SATA (or Serial ATA) or SAS (Serial Attached SCSI). With Sata we have 3gbps and 6gbps ports – use 6gbps ports for SSDs and 3gbps ports for hard drives.
With SAS one type of connector is sata compatible (if the chipset supports it) while the other two arn’t. SAS drives tend to be classed as nearline (cheaper, slower drives, though often better than consumer drives), and classic drives.
If you’re using consumer grade gear, go with sata. If you’re running a server go with SAS. If you’re expected to use IDE or Scsi in this day and age… well, you’re running a museium of old computers.