backbone
The current popular standard is the SATA (serial AT Attachment) interface.
Enhanced Integrated Drive Electronics (EIDE)
Integrated Drive Electronics (IDE) refers to a standardized interface that provides slots for connecting hard drives to the motherboard of a computer. SCSI, known as Small Computer Systems Interface, provides a universal interface for connecting such devices as disc drives, hard drives, plotters and scanners.
The USB interface standard connects external hardware to your computer- everything from webcams to external hard drives to your Ipod. Without it you would be unable to access many functions of cameras and other devices that allow you to upload things to the internet.
The most common problem with large hard drives is computer crashes.
Modern hard drives connect to the hard drive using a SATA cable. Older ones use a larger, slower IDE cable.
A PATA can be used to connect older hard drives to a computer internally, as it was a common interface. The PATA format has largely been replaced by SATA.
They all store information.
They both... used as storage
Standard CMOS ConfigurationThe standard CMOS configuration screen includes settings for items such asDateTimeFloppy disk drive types for drives A: (first floppy disk drive) and B: (second floppy disk drive)Hard drives connected to the IDE interface
sata
There are many portable external hard drives which would fit into most standard size pockets.