PATA:

It stands for Parallel Advanced Technology Attachment. It was also called ATA / IDE in it’s earlier days. It is a bus interface used for connecting secondary storage devices like hard disks, optical drives. It was first introduced in 1986 by Western Digital and Compaq.

SATA:

It stands for Serial Advanced Technology Attachment. It is a bus interface that connects hard disks, optical drives. It was introduced in 2001 and replaced PATA. SATA has more advantages than PATA hence making it’s demand more.

Differences:

PATA

Cable pins : 40
Transfer Speed: 8.3MB/s later increased to 133MB/s
Cable Length and size : can extend upto 18 inches, and has a bigger size (width)
Bus: It uses different wires to carry data and information
Hot plugging: No hot swapping, i.e Cannot replace hard drive, CD-ROM drive, power supply, or other device with a similar device while the computer system using it remains in operation.
Cost and power consumption : High
Jumpers : There could be more than one harddrive. To connect multiple IDE drives, the ribbon cables are chained from one to the next. The computer has no idea which is the main drive, from which to load the OS.

SATA

Cable pins : 7
Transfer Speed: Quite an improvement from its predecessor. Highest speed being 16GB/s
Cable length and size: can extend upto 1 meter and has a smaller size (width).
Bus: It carries data in a single bus
Hot plugging: It is hot swappable
Cost and power consumption : Low
Jumpers: It doesn't use jumpers. Each drive connects directly to the motherboard. BIOS has the settings where one can see which drive is the primary drive.