80 pin cables are generally newer than 40 pin cables, and can, in most cases, transfer data at a faster rate. The extra 40 wires are not actually pins, but wires separated the pins that actually carry data. The purpose of these is to reduce signal interference.
EIDE cable uses a 40-pin connector at the end of the cable to interface with the drive.
ATAPI.
The cable connects between the motherboard of the computer and the hard-drive or optical drive.
40
EIDE
PATA can be expressed as an IDE or EIDE cable as well.
Typically EIDE cables connect to IDE Hard-drives and optical drives such as CD and DVD Drives. The cable connects between the motherboard of the computer and the hard-drive or optical drive. Normally most motherboards have two idea buses. You can have to drives per cable. So a total of 4 drives.
Cable size, data transfer speed, and SATA is newer technology.
A maximum of two devices can be placed on an EIDE / PATA cable. Not all cables will include two connectors for doing so, though.
The floppy drive cable would be about half the width than the other.
The most important reason the PATA connector is present is the PATA connector can be used for EIDE drives such as a CD or DVD drive.
Why is there confusion between EIDE and SCSI drive interface standards